Gibson Muffler Questions?

[HotRod8]

I know a few on this sight (2000LtdKen and RockyMtnRay for sure) have the Gibson muffler with the JBA headers and have reported good results for towing performance. My main question is which Gibson are you using? Is it one of these:
http://www.gibsonperformance.com/products.asp?pid=18352
I guess my other questions are is it louder, quieter or about the same as stock, with the JBAs? Did you replace just the muffler (and headers of course) or other parts of the system as well, piping for example? I assume that this Gibson muffler needs to be welded into the stock pipes? Without going and looking under my truck I don't recall how the existing muffler "fits in", I seem to think it's part of the tail pipe assembly, all one piece from behind the Y-pipe all the way back.

[2000LtdKen]

Originally Posted by HotRod8

I know a few on this sight (2000LtdKen and RockyMtnRay for sure) have the Gibson muffler with the JBA headers and have reported good results for towing performance. My main question is which Gibson are you using? Is it one of these:
http://www.gibsonperformance.com/products.asp?pid=18352
I guess my other questions are is it louder, quieter or about the same as stock, with the JBAs? Did you replace just the muffler (and headers of course) or other parts of the system as well, piping for example? I assume that this Gibson muffler needs to be welded into the stock pipes? Without going and looking under my truck I don't recall how the existing muffler "fits in", I seem to think it's part of the tail pipe assembly, all one piece from behind the Y-pipe all the way back.

Hey HotRod8,

I followed Rays advice and purchased the Gibson model 788500S muffler. Had a local shop weld it in for me for about $40. It is louder than stock but not as loud as a performance muffler. It has a nice rumble to it when starting, idling and leaving a stop sign but then quiets down at highway speeds. I used the stock pipes because I did not want to lose low end torque. I didn't really notice too much of a change in the power just from this.

Then one day, my son and I decided that we didn't want any more skin on our knuckles so we put on the JBA headers. 11 hours later we were done. You could feel a differenc right away. After about a week or so you could really feel the difference as the computer starts getting adjusted to the new setup and the truck gets real peppy. A joy to tow with. I used to run premium gas when towing to prevent pinging. My truck has not pinged since the JBA installation and I can use regular gas towing.

HTH,

Ken

[RockyMtnRay]

Originally Posted by HotRod8

I know a few on this sight (2000LtdKen and RockyMtnRay for sure) have the Gibson muffler with the JBA headers and have reported good results for towing performance. My main question is which Gibson are you using? Is it one of these:
http://www.gibsonperformance.com/products.asp?pid=18352
I guess my other questions are is it louder, quieter or about the same as stock, with the JBAs?

I have...and recommend the 788500S...it's the stainless steel version of the longest of their "superflow" mufflers. Reasons for this particular muffler:

• The stainless version is made from slighly heavier gauge steel. So, in addition to being much longer lasting than the aluminized version, it's much less likely to produce the dreaded 2k drone.
• Gibson mufflers work like no other aftermarket muffler. Basically there's a perforated tube running the entire length of the muffler case that's attached to the inlet pipe; a 2nd perforated tube running parallel to the inlet tube is connected to the muffler outlet. The perforations on the inlet tube are not just holes but more like scalloped "scrapers" such as you find on on a cheese grater...and are pointed toward the inlet to essentially scrape the incoming gas out of the tube while simultaneously breaking up the sound waves. The outlet tube has similar "grater" type holes except these are aimed toward the outlet and (1) further break up the sound waves while (2) producing a laminar flow in the outlet. There are no chambers per se (the entire muffler cannister is a single chamber) and there is no sound absorbing material like fiberglass. The muffler muffles sound by fracturing the the sound waves through the graters and causing the gasses to cross between the two tubes. Because the gas transfer effectiveness between the tubes is related to tube length, the longest case (24 inches) that Gibson makes has (1)the least backpressure and (2) is also the quietest.

The net effect of this unique construction is the muffler has a soft rumble at small throttle openings when the RPM is below 1200 (basically just a bit louder than stock). Between 1200 and about 2000 RPM at small to moderate throttle openings, it makes a sort of growl (not a distinct rumble) that is definitely louder than stock but still much quieter than any other aftermarket muffler. At RPMs over 2000 or at high throttle openings, it just makes a "whoosh" that's a tad louder than the stock "whoosh" but has no rumble or growl effects at all. It is not a muffler for someone who either wants the nearly complete silence of the stock system nor the characteristic "V8 sound" of most aftermarket mufflers. But though detectably louder than stock (especially between 1200 and 2000 RPM), it's still quite bearable for extended periods of towing...and that's coming from a guy who has both sensitive hearing and very little tolerance for noise.

Did you replace just the muffler (and headers of course) or other parts of the system as well, piping for example?

Yes, muffler only and for two reasons.

First, low end torque will be best maintained if you keep as much as possible of the OEM 2 3/8 inch pipe. Like most aftermarket "catback systems", the Gibson Single Sideswept system uses slightly larger 2 1/2 inch pipe. Larger pipe...even that 1/8 inch...reduces low end torque.

Second, I strongly suspect that the dreaded 2K drone is minimized if you keep the OEM 2 3/8 pipe. I have a bit of that drone but it's not obtrusive at all. Comparing the reports from those who installed the complete bolt-on Gibson SS "system" with those of us who simply replaced the muffler, my impression is those with the "system" and its 2 1/2 inch pipe are far more likely to complain about 2k drone.

I assume that this Gibson muffler needs to be welded into the stock pipes? Without going and looking under my truck I don't recall how the existing muffler "fits in", I seem to think it's part of the tail pipe assembly, all one piece from behind the Y-pipe all the way back.

There's a donut connector just behind resonator on the stock system where the stock muffler can be disconnected. The shop that did my install (1) cut the OEM pipe just behind the stock muffler and (2) disconnected the stock muffler at the donut connector. They then welded the rear of Gibson to the remaining pipe and welded in approximately 10 inches of 2 1/2 pipe between the front of the Gibson and the donut connector (the stub pipe was welded here as well). I won't be able to readily go back to the stock muffler but have zero interest in doing so either.

Final notes: Unlike most people, I installed the JBA headers first...before changing the muffler. I was working from the concept that the stock manifold is the largest restriction in the exhaust system. So I can't speak to any increase in sound of using the this muffler with or without headers but suspect it won't be much. I can definitely state that you will not (as Ken notes in his report) get much, if any, torque increase until you have headers installed...for the very reason that the OEM muffler is muchly secondary to the OEM manifold in terms of restriction.

That all being said, I definitely noticed a torque increase from installing the muffler in addition to the JBAs...the gain was somewhere around half the gain of the JBAs by themselves. And even better, the muffler had the unexpected effect of lowering the peak torque RPM by about 100~200 RPM: my engine is now making peak torque at 3200 RPM and the point at which the torque increase from the headers starts is closer to 2500 RPM than the 2700 it was before the muffler. And, of course, the lower the RPM that peak torque is obtained, the better for towing.

The bottom line is that Gibson muffler + JBA headers is a very good combo for towing.

[HotRod8]

Exactly, Exactly, what I was looking for; Thank-you both very much.
I already have the JBAs and am looking to do more to improve towing performance, although I feel it is pretty good already. I also have no desire to have one of the "V8 Sound" (to me this just means to darn loud) exhaust systems. I already knew not to go the Cat-Back route, I was just wondering about how you physically "plumbed" in the Gibson; Ray has answered that very well.
Rod

[Tankerhank]

Originally Posted by RockyMtnRay

I have...and recommend the 788500S...it's the stainless steel version of the longest of their "superflow" mufflers. Reasons for this particular muffler:

• The stainless version is made from slighly heavier gauge steel. So, in addition to being much longer lasting than the aluminized version, it's much less likely to produce the dreaded 2k drone.
• Gibson mufflers work like no other aftermarket muffler. Basically there's a perforated tube running the entire length of the muffler case that's attached to the inlet pipe; a 2nd perforated tube running parallel to the inlet tube is connected to the muffler outlet. The perforations on the inlet tube are not just holes but more like scalloped "scrapers" such as you find on on a cheese grater...and are pointed toward the inlet to essentially scrape the incoming gas out of the tube while simultaneously breaking up the sound waves. The outlet tube has similar "grater" type holes except these are aimed toward the outlet and (1) further break up the sound waves while (2) producing a laminar flow in the outlet. There are no chambers per se (the entire muffler cannister is a single chamber) and there is no sound absorbing material like fiberglass. The muffler muffles sound by fracturing the the sound waves through the graters and causing the gasses to cross between the two tubes. Because the gas transfer effectiveness between the tubes is related to tube length, the longest case (24 inches) that Gibson makes has (1)the least backpressure and (2) is also the quietest.

The net effect of this unique construction is the muffler has a soft rumble at small throttle openings when the RPM is below 1200 (basically just a bit louder than stock). Between 1200 and about 2000 RPM at small to moderate throttle openings, it makes a sort of growl (not a distinct rumble) that is definitely louder than stock but still much quieter than any other aftermarket muffler. At RPMs over 2000 or at high throttle openings, it just makes a "whoosh" that's a tad louder than the stock "whoosh" but has no rumble or growl effects at all. It is not a muffler for someone who either wants the nearly complete silence of the stock system nor the characteristic "V8 sound" of most aftermarket mufflers. But though detectably louder than stock (especially between 1200 and 2000 RPM), it's still quite bearable for extended periods of towing...and that's coming from a guy who has both sensitive hearing and very little tolerance for noise.

Yes, muffler only and for two reasons.

First, low end torque will be best maintained if you keep as much as possible of the OEM 2 3/8 inch pipe. Like most aftermarket "catback systems", the Gibson Single Sideswept system uses slightly larger 2 1/2 inch pipe. Larger pipe...even that 1/8 inch...reduces low end torque.

Second, I strongly suspect that the dreaded 2K drone is minimized if you keep the OEM 2 3/8 pipe. I have a bit of that drone but it's not obtrusive at all. Comparing the reports from those who installed the complete bolt-on Gibson SS "system" with those of us who simply replaced the muffler, my impression is those with the "system" and its 2 1/2 inch pipe are far more likely to complain about 2k drone.

There's a donut connector just behind resonator on the stock system where the stock muffler can be disconnected. The shop that did my install (1) cut the OEM pipe just behind the stock muffler and (2) disconnected the stock muffler at the donut connector. They then welded the rear of Gibson to the remaining pipe and welded in approximately 10 inches of 2 1/2 pipe between the front of the Gibson and the donut connector (the stub pipe was welded here as well). I won't be able to readily go back to the stock muffler but have zero interest in doing so either.

Final notes: Unlike most people, I installed the JBA headers first...before changing the muffler. I was working from the concept that the stock manifold is the largest restriction in the exhaust system. So I can't speak to any increase in sound of using the this muffler with or without headers but suspect it won't be much. I can definitely state that you will not (as Ken notes in his report) get much, if any, torque increase until you have headers installed...for the very reason that the OEM muffler is muchly secondary to the OEM manifold in terms of restriction.

That all being said, I definitely noticed a torque increase from installing the muffler in addition to the JBAs...the gain was somewhere around half the gain of the JBAs by themselves. And even better, the muffler had the unexpected effect of lowering the peak torque RPM by about 100~200 RPM: my engine is now making peak torque at 3200 RPM and the point at which the torque increase from the headers starts is closer to 2500 RPM than the 2700 it was before the muffler. And, of course, the lower the RPM that peak torque is obtained, the better for towing.

The bottom line is that Gibson muffler + JBA headers is a very good combo for towing.

This is where I get a little confused

Don't do the Gibson CAT-BACK exhaust as the 1/8" increase in pipe size will reduce torque by decreasing back pressure too much?

Do headers as the stock exhaust manifold is the most restrictive of the whole exhaust system and headers will open things up (less back pressure)?

Do not do K&N cold intake as it will reduce torque, just do the K&N filter?

I understand TOO open of an exhaust will not help create low end torque, so you are saying with headers moving to the Gibson CAT-BACK will push the system "over the edge" and start to loose torque instead of improve it? I was reading on the Gibson site where they say the combo of their single side CAT-BACK and headers greatly improves low end torque for towing, is the difference in their headers vs the JBA? What about Hooker headers?

Now help me with the K&N intake too; open up the exhaust but not the breathing? Toyota uses that large "looped" intake manifold to create torque so the gen II K&N intake is a bad thing?

I appreciate all the help I can get.... Thanks

[ProEdge]

I tow a TC Travel Trailer..
The Trailer & Kit, clock in just under 5000lbs..
On the Dual Exhaust issue..
I have an 06 Tundra D/C with the TRD Dual Exhaust..
My brother has an 05 Tundra D/C regular factory exhaust..
Both vehicles have the same kms on them..
Now.. At the higher RPM you can definetly feel more torque, power and acceleration with the Dual Exhaust Tundra..
At the lower RPM's, the low end torque feels the same between both Tundra's if not abit higher with the Dual Exhaust Tundra..
We have compared our Tundra's and the Dual Exhaust seems to out perform the regular exhaust at both the low and high RPM's..
The comparison's were done dry, not towing a trailer.
Any feedback appreciated..

[RockyMtnRay]

Originally Posted by Tankerhank

This is where I get a little confused

Don't do the Gibson CAT-BACK exhaust as the 1/8" increase in pipe size will reduce torque by decreasing back pressure too much?

You have it backwards. Increasing the pipe size INCREASES THE BACKPRESSURE (not reduces it) at low to mid RPM. Yes, bigger pipe = MORE backpressure at low RPM. Intuition is wrong at low RPM. The reason is the larger pipe allows more cooling, more loss of exhaust velocity, and the gas has to be pushed out instead of keeping its heat energy and velocity. Pushing the gas out the pipe detracts from the engine torque. This concept that an exhaust pipe is like a garden hose and bigger is better for breathing is correct at high gas velocities (high RPM) but is very, very wrong at low RPMs because the thermodynamic cooling effects are larger than the effects of wall friction on gas flow.

Do headers as the stock exhaust manifold is the most restrictive of the whole exhaust system and headers will open things up (less back pressure)?

Yes, headers do have less backpressure...and backpressure is always bad for torque on the pre-05s. There is no such thing with the pre-05 engine as "needing some backpressure". The '05 and later engine (which do have valve overlap at higher RPM (because of the VVTI design) can be helped by some backpressure.

Do not do K&N cold intake as it will reduce torque, just do the K&N filter?

The K&N is NOT a cold intake. It's a HOT air intake ...it sucks mostly hot engine compartment air (air dam or not). The stock intake IS a cold intake...it pulls air out of the inner fenderwell.

I understand TOO open of an exhaust will not help create low end torque, so you are saying with headers moving to the Gibson CAT-BACK will push the system "over the edge" and start to loose torque instead of improve it? I was reading on the Gibson site where they say the combo of their single side CAT-BACK and headers greatly improves low end torque for towing, is the difference in their headers vs the JBA? What about Hooker headers?

Now help me with the K&N intake too; open up the exhaust but not the breathing? Toyota uses that large "looped" intake manifold to create torque so the gen II K&N intake is a bad thing?

I appreciate all the help I can get.... Thanks

Gibson' marketing has to be taken with a very large grain of salt. They make huge amounts of profit off the 5 feet or so or 2.5 inch tubing in their "system" pricing versus the pricing of just the muffler that's used in that "system". The 2.5 inch pipe in their "system" will undoubtedly help high end horsepower and will also undoubtedly move the peak torque RPM above the stock 3400. It won't help the bottom end torque so necessary for towing. My experience (and others) is that keeping the stock pipe is a key to keeping the peak torque at a low RPM.

I have no first hand knowlege of th Gibson headers...they appear to be a decent mid length design. Hooker headers are notorious for thin metal and shoddy construction...low price but probably won't last more than a year or two (probably less than that in towing). A major advantage of JBA (beside 1st class construction and factory ceramic coatings) is the fire cone collector. Instead of a flat plate, JBAs have conical projection that helps the gasses merge inside the collector, hence causing these "shorty" headers to act like a long tube header. JBAs are much more expensive but are good value for the money.

The stock intake manifold on the pre-05 V8s has extremely long intake runners to maximize low RPM torque (via a ram air effect). The stock intake air box size and ducting is specifically tuned to work with those long intake runners. That air box plays a very key role in the intake tuning through the Hemholz tuning effect. A few (not K&N) aftermarket intake makers (Volant being one) do understand the criticality of including a tuned airbox in their systems.

As for K&N versus stock intakes, the K&N does not flow any better than the stock intake at any RPM. What it does do is introduce a bit of shadowing on the Mass Air Flow sensor at high flow rates that causes that sensor to under report air flow into the engine. The ECU then slightly reduces fuel flow when in open loop conditions and thus slightly leans the mixture. A slightly leaner than stock mixture actually produces somewhat better power than the stock mixture at high power. Hence, the K&N does help top end horsepower but not for the usually mentioned reason of "flowing better". Worse, the K&N sucks in mostly hot engine compartment air; especially at lower speeds and lower engine RPMs (towing conditions). Hot air = less power. Period. If you have to have an aftermarket intake, at least get a decent one such as the Volant that (1) is tuned for low RPM and (2) is actually a true cold air intake. I personally wouldn't mount a K&N intake on my truck if you paid me $10,000 to do it...IMHO, a K&N is truly terrible for towing torque (not to mention the atrociously loud sucking sound they make).

[jimdejet]

I tried the Gibson SS muffler that Ray and others have used for 5,000 miles. The muffler did add torque for towing along with the JBA headers. My wife and I missed the oem muffler quietness and had the original muffler reinstalled. We like the sound much better now. Now we have minimal 2,000 rpm dreaded drone.

Maybe we are more sound sensitive than others. Also the Tundra has a camper shell and now I wonder if that contributed to a heavier exhaust sound being heard in the cab? Also a Unichip is installed and could this also contribute to additional exhaust noise?

Has anyone put an extension on the end of the tail pipe for the exhaust to exit in cleaner air instead of the oem way of directly behind the rear tire? If so did the exhaust sound change from the oem sound?

[Bad Gas]

jimdejet, i have used many diifferent aftermarket mufflers, including Gibson. I got rid of the 2k drone by cutting the tailpipe off, so that the exhaust system dumps just past the axle. Exaust flow is directed down, no longer out the pass side of the truck. It seems the factory tailpipe resonance contributes to drone. Now, this should not be done on an SUV, due to the possibility of introducing CO into passenger compartment, big no no. Also any moisture in exhaust will accelerate rust, (see f150 pass wheel corrosion issues). Also you'll dump your exhaust on your trailer. Give and take.

[H2O_MAN]

Originally Posted by Bad Gas

I got rid of the 2k drone by cutting the tailpipe off, so that the exhaust system dumps just past the axle.
Exaust flow is directed down, no longer out the pass side of the truck.

Interesting...

[jimdejet]

Interesting about shortening the exhaust and pointing it to the ground with a decrease in the 2K drone.

From experience on 2-stroke dirt bikes many years ago with after market noisier exhaust we were able to take a lot of the bark out by cutting a 4" piece of motorcycle tire tubing and sliding it over the end of the muffler 2". This left 2" of tube sticking out in the air. Big difference in less noise.

I wish that I had hose clamped a 4" to 8" piece of old radiator hose on the end of the exhaust before converting from the Gibson muffler to oem and drove for a few miles for any difference in sound.

[v8Toilet]

Originally Posted by jimdejet

I tried the Gibson SS muffler that Ray and others have used for 5,000 miles. The muffler did add torque for towing along with the JBA headers. My wife and I missed the oem muffler quietness and had the original muffler reinstalled. We like the sound much better now. Now we have minimal 2,000 rpm dreaded drone.

Maybe we are more sound sensitive than others. Also the Tundra has a camper shell and now I wonder if that contributed to a heavier exhaust sound being heard in the cab? Also a Unichip is installed and could this also contribute to additional exhaust noise?

Has anyone put an extension on the end of the tail pipe for the exhaust to exit in cleaner air instead of the oem way of directly behind the rear tire? If so did the exhaust sound change from the oem sound?

If you are getting a drone with the stock muffler you might have an exhaust leak. The most likely place you'll get an exhaust leak is at the connection just after the resonator. If the installer didn't put a new gasket in the connection just after the resonator and just reused the old one than it will most likely leak.

Also if you so much as have a pin hole in your exhaust system due to shoddy welding you'll have a nosier exhaust system. Any hole in the exhaust system will also cause you to loose some lower end torque depending on the size of the leak.

Restrict the exhaust system at the tail pipe without completely blocking it off and feel around those connections. Chances are you'll hear it hissing if it leaks badly.

[seacopper]

I'm like the rest, want to save money, but add a little torque. I read a lot of what you say and what I have boiled it down to is this, JBA Headers and a Gibson SS muffler for both torque and horses vice dual exhaust for my 05 Tundra V-8 DC. Can you recommend a size for the Gibson and also how does the Magnaflow compare? Thanks.
Seacopper

[RockyMtnRay]

Originally Posted by seacopper

I'm like the rest, want to save money, but add a little torque. I read a lot of what you say and what I have boiled it down to is this, JBA Headers and a Gibson SS muffler for both torque and horses vice dual exhaust for my 05 Tundra V-8 DC. Can you recommend a size for the Gibson and also how does the Magnaflow compare? Thanks.
Seacopper

Strongly recommend the longest model with the 2.5 inch inlet/outlet. That would be SKU 788500S in stainless (drop the S from the end for aluminized). Recommend the stainless for a bit heavier gauge metal that won't rust out and is less likely to have drone. Dimensions are 2.5'' X 2.5'' offset inlet/outlet, 6'' diameter, 24'' body, 30'' overall length (it's a bit smaller in diameter, but actually a tad bit longer than the stock muffler). Gibson mufflers use a parallel internal perforated tube design...the long case allows the most area for gas transfer between the perforated tubes and thus the lowest muffler backpressure (also the most sound muffling). Gibson sells shorter designs but I strongly recommend against buying one if towing and torque are the objectives.

Magnaflow is a totally different design...basically a relatively quiet glass pack type muffler. Probably about equal on performance gains but likely to be a lot louder than the Gibson at high throttle openings that are typical when towing. Magnaflow mufflers are a typical "performance" design...the more you open the throttle the louder they get. Great for regular/spirited driving; not so good for hours of towing, especially hours of mountain towing. The reason I (and many others) promote Gibson mufflers for towing is they stay pretty quiet at high throttle openings yet give a very decent mid range torque boost.

[tomhole]

Where's the best place to get the Gibson? Most places on the web are $150, shipped.

Thanks,

Tom