Has anyone had good or bad luck with Flow Master's Dual Exhaust for the Tundra? I have heard nothing but bad things about the TRD Dual Exhaust. I just purchased the Flow Master Exhaust Kit, and I am apprehensive from installing it seeing how everyone says dual exhaust reduced their tourque.
I installed duals with the Flowmaster 50 series. The pipes were installed by the shop and they did an excellent job. I have not noticed any performance drop since. I have an 03 Tundra and it sounds great.
That's good to hear, I am anxious to get them installed, but all the negatives I heard about the TRD exhaust I was like damn I hope the flow masters work better.
Best thing to do is have it installed and get your own conclusions...
From what I have read, its not worth having them.. Great sound but takes longer to get up to speed and more gas usage.
That's good to hear, I am anxious to get them installed, but all the negatives I heard about the TRD exhaust I was like damn I hope the flow masters work better.
Nearly all catback dual exhausts (regardless of brand) are going to at least somewhat hurt your low end torque. The problem with dual pipes (unless they're real small (like 1 and 7/8 inch diameter or smaller) is they let the exhaust gases slow down and cool down much more than the stock single 2 and 3/8 inch pipe. When the exhaust gas cools and becomes stagnant, it gets dense and acts like a plug that has to be pushed out by incoming gasses from the engine. The net result is that dual pipes actually have more backpressure than the stock single pipe at low to mid RPM. However, once you get the engine near redline (over about 4500 RPM) the duals begin to help a bit because the gas no longer has a chance to slow down and cool...and wall friction in the single pipe becomes a significant issue. So at very high RPMs the common belief that duals have lower backpressure is true....but at low RPMs it's exactly the opposite, the duals have more backpressure. And the common misperception that the engine "needs" backpressure to make the most power is simply not true...backpressure is bad for torque. The result of all this is you will lose low end torque.
The additional sound from the duals with a louder muffler (and tendancy to use a heavier foot to make that sound) causes a lot of folks to feel they haven't lost any low end torque. But the torque loss is real and well documented.
The main differences between TRD and Flowmaster exhausts are cost, appearance, and quality/loudness of the exhaust sound. TRDs (which are basically relabeled Borlas) are an absorption (like glasspack) type muffer & resonator; Flowmasters are chambered resonator type mufflers. The TRD muffler actually might flow a bit better at very high RPM because it's a more straight through design.
thats some good info... Seeing how dual exhaust increases the overall volume of air flow from the cat back, I wonder why exhaust manufacturers don't compensate by reducing the size of the dual pipes so they optimize air flow over the entire RPM range. Especially for 4x4 trucks most of us want low end grunt and not high HP at high RPM's. It seems they should have dual exhaust that sound/look good and have smaller diameters so the low end torque is maintained, or they should shorten the pipe length and have the exhaust exit before the rear tires. I have actually seen some custom exhaust that exit before the rear tires and it looks great when done correctly.
To me it should'nt be necessary to put headers or a s/c on just so I can have dual exhaust, but hey who am I...
Ford tried that exit in front of the rear wheels trick when they introduced the new style F series five or more years ago. They found out the hard way that the corrosive/damp emissions from the tailpipes corroded the finish on the steel and alloy rear wheels especially in cold climate areas. They replaced countless wheels under warranty before they relocated the tailpipe outlet farther to the rear. I have a hunch that trucks with tailpipes too small would present another problem with noise. Or worse yet that whistle or compressed air sound you hear sometimes with vehicles that have restricted mufflers or crimped tailpipes.
Larry
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2004 Tundra V8 Limited Access Cab 4X4, Michelin 265/65/R17 LTX-AT2's, Auto Dim Comp/Temp Mirror, Aero Turbine #2525 muffler, Access Roll Up Cover, Optima D31A battery, Multi-Vex adaptive outside mirrors, Eclipse AVN5510 Nav unit and Sirius SIR-ECL1 tuner, as of 10/07 pictures in my photo gallery
If a combo of all these whizz bangs met their claims you'd have to siphon gas out of your tank every second day and sell the excess horsepower on the third????
If your engine doesn't consume ANY oil it will seize???
Some people should not be allowed access to tools without books!!!
I like it a lot but mainly for it's sound. Preliminary mileage figures say not a noticeable difference so far. If there are any power differences I am unable to feel them. It's only been on a few weeks and our weather has been windy or rainy or both so it'll be a few months before I know of any changes. I will caution that this is not a low cost muffler, I paid $192 and they had a free shipping offer at the time. It is entirely constructed from 304 stainless but there are others (Borla comes to mind) that use that construction. I took a chance and fortunately for me I love the sound it produces and more than that no objectionable drone or vibration. I only replaced the existing muffler and added a SS rolled outlet tip at the stock location.
Larry
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2004 Tundra V8 Limited Access Cab 4X4, Michelin 265/65/R17 LTX-AT2's, Auto Dim Comp/Temp Mirror, Aero Turbine #2525 muffler, Access Roll Up Cover, Optima D31A battery, Multi-Vex adaptive outside mirrors, Eclipse AVN5510 Nav unit and Sirius SIR-ECL1 tuner, as of 10/07 pictures in my photo gallery
If a combo of all these whizz bangs met their claims you'd have to siphon gas out of your tank every second day and sell the excess horsepower on the third????
If your engine doesn't consume ANY oil it will seize???
Some people should not be allowed access to tools without books!!!
You have surely down your research. I have to agree I believe some of the torque is missing but very minor. The only way I can tell is before the flows when the engine was in second gear I would turn tap the gas and it felt like the truck would run out from under me. The jump is still there just not as intense but very mean sounding.
thats some good info... Seeing how dual exhaust increases the overall volume of air flow from the cat back, I wonder why exhaust manufacturers don't compensate by reducing the size of the dual pipes so they optimize air flow over the entire RPM range. Especially for 4x4 trucks most of us want low end grunt and not high HP at high RPM's. It seems they should have dual exhaust that sound/look good and have smaller diameters so the low end torque is maintained, or they should shorten the pipe length and have the exhaust exit before the rear tires. I have actually seen some custom exhaust that exit before the rear tires and it looks great when done correctly.
Larry did an excellent job of addressing the issues that arise with dumping the exhaust in front of the rear tires...nothing needs to be added to that.
As for using smaller pipes to keep up the exhaust velocity, well, now we're getting into issues of marketing to guys (mostly) and particularly into issues of trying to convince guys that "wimpy" little pipes are going to provide better performance than "manly" big pipes are going to provide. Hopefully without sounding too crude and crass here, we do need to realize that an awful lot of exhaust system purchasing is pretty tightly tied to masculine self-images where "bigger is better". On a honkin' big 454 cu in motor, 3 inch (or even larger) dual pipes are a perfect size for low end torque. But we're working with a pretty small 285 cu in engine...and the ideal dual pipe size (well under 2 inches) just isn't, well, very "manly". And if it isn't "manly" in appearance, it's simply not going to sell at all well...no matter what the dyno results are.
Now, for those of us who don't tightly link our masculinity to the size of our truck's exhaust pipes , the smart approach is to simply replace the muffler (and muffler only) and leave the rest of the piping alone at the smartly engineered 2 and 3/8 inch diameter single pipe. No it won't look "tough" but it can sound pretty tough (if you use a muffler designed for a a "full" sound with broad appeal (e.g. Flowmaster)) or it can be pretty quiet but very free flowing for purposes like towing (e.g. by using the biggest Gibson muffler).
The bottom line is that catback duals look tough and sound tough but definitely hurt the low end grunt. Catback single pipe "systems" invariably use too-large 2.5 inch pipe and drain your wallet, add some drone, and slightly hurt torque...but they can sound pretty tough and often give you a real nice exhaust tip. Just replacing the muffler usually keeps the torque (sometimes actually increases it...there are dyno results in The Garage showing that Spintech mufflers do improve peak torque) and will give as mean a sound as you want...but the look isn't very tough. Your choice, your money.
Nearly all catback dual exhausts (regardless of brand) are going to at least somewhat hurt your low end torque. The problem with dual pipes (unless they're real small (like 1 and 7/8 inch diameter or smaller) is they let the exhaust gases slow down and cool down much more than the stock single 2 and 3/8 inch pipe. When the exhaust gas cools and becomes stagnant, it gets dense and acts like a plug that has to be pushed out by incoming gasses from the engine.
Although this is true in theory, so is driving with your windows down effects aerodynamics and hurts performance. A lame comparison...true, the point is just because something in theory is true, it doesn't mean that it will be a noticeable.....or a better word....a SIGNIFICANT difference.
Also...don't be fooled into thinking it's just pipe dia, the pipes wall thickness, the type of muffler, the quality of bends in the pipe, all play a role in exhaust flow....even the tips.
With 2 1/2 pipe there are noticeable losses by some people, with 2.0 and 2 1/4 many many people testify no noticeable loss on the low end, and definate gains above 3000RPM. I am one of them. I would give up any other mod I've done before my dual exhuast....including the unichip that was a big performance gain....The truck a (V8) is meant for dual....it's that simple
Oh...BTW....forget about flowmasters....do yourself a favor and go with magnaflows...I've tried both...and IMO no comparison.
Here is a listen (please excuse the dyno fans) .These are absolutely quiet on the road (unless you really get on it).
With 2 1/2 pipe there are noticeable losses by some people, with 2.0 and 2 1/4 many many people testify no noticeable loss on the low end, and definate gains above 3000RPM. I am one of them. I would give up any other mod I've done before my dual exhuast....including the unichip that was a big performance gain....The truck a (V8) is meant for dual....it's that simple
Your system is one of the exceptions I was thinking of when I wrote "nearly all". Certainly, a custom dual system like yours that has a properly located H-Crossover (or even better, X-Crossover) and exactly the right components including mandrel bent tubing usually can avoid low-end torque loss and will get improved torque in the higher RPMS. Although I gotta say, you might have done even better in the sub-3000 RPM range with the 2 inch pipe that was recommended by, IIRC, V8Toilet (and others) at the time you had your system designed/fabricated.
However, my remarks were targeted toward the typical folk like our original poster who buy an off-the-shelf "system" that simply replaces the stock muffler with a single inlet, dual outlet muffler (whether it be Flowmaster or TRD) and has dual 2.5 inch (or larger) pipes to the back of the truck. And when it comes to those off-the-shelf "systems", I'll stand by my statement that low end torque loss is all but guaranteed.
You are indeed proof that if someone wants to invest time, energy, and enough money to have a knowlegeable performance shop craft a custom crossover system, good to very good dual exhaust performance can be obtained. But most folk don't have that time, energy, or money...and won't get good performance from a bolt-on, off-the-shelf system that basically just replaces the stock muffler and single tailpipe with dual post-muffler tailpipes.
I've got 2 1/2" dual tail pipes on mine with the big 3 1/2" tips. I've never noticed the loss of torque, but you are probably right since I did notice it on the dyno charts quite awhile back. Here's an idea that might let us prove it one way or the other: There's been some talk in another thread about converter stall speed. Since all us V8 guys have one of these, whether we wanted it or not, what if we compared stall speed RPM? The way I understand it, if you are down on torque, your stall speed would be down a bit. If you have more torque than the rest of us (V8 Toilet) wouldn't your stall speed RPM be up a bit higher? I know that if you "cam up" an automatic transmission car to where you kill the engine's low end, you can get some of the "off the line" performance back with a "high stall" converter. Also, some aftermarket companies sell a "low stall" converter for diesel pickups that put out a lot of torque down really low. Maybe we could dyno test our engine's low speed torque by using our own built in dynos (converters). It would just have to be remembered that you run some risk in doing this, such as drive train damage, and overheating your transmission fluid. When I worked in the shop, we would chock the wheels, hold the brakes, do the test really quick, and then slip it into neutral and run at high idle to cool the fluid back down. GM schools warned that you ran the risk of causing minute welds on the contact surfaces of the ring and pinion while performing a stall test with their large displacement V8s.
__________________ ADDING POWER HAS NEVER BEEN SO FAST!
I've got 2 1/2" dual tail pipes on mine with the big 3 1/2" tips. I've never noticed the loss of torque, but you are probably right since I did notice it on the dyno charts quite awhile back. Here's an idea that might let us prove it one way or the other: There's been some talk in another thread about converter stall speed. Since all us V8 guys have one of these, whether we wanted it or not, what if we compared stall speed RPM? The way I understand it, if you are down on torque, your stall speed would be down a bit. If you have more torque than the rest of us (V8 Toilet) wouldn't your stall speed RPM be up a bit higher? I know that if you "cam up" an automatic transmission car to where you kill the engine's low end, you can get some of the "off the line" performance back with a "high stall" converter. Also, some aftermarket companies sell a "low stall" converter for diesel pickups that put out a lot of torque down really low. Maybe we could dyno test our engine's low speed torque by using our own built in dynos (converters). It would just have to be remembered that you run some risk in doing this, such as drive train damage, and overheating your transmission fluid. When I worked in the shop, we would chock the wheels, hold the brakes, do the test really quick, and then slip it into neutral and run at high idle to cool the fluid back down. GM schools warned that you ran the risk of causing minute welds on the contact surfaces of the ring and pinion while performing a stall test with their large displacement V8s.
I regularly see the stall RPM on my truck's TC...it's about 2200 RPM...when I'm towing at high altitude. Happens when I'm at or above 9000 feet where the engine torque is half or less of the sea level torque. With my 3700 lb trailer in tow and 500 to 800 lbs of people/cargo in the truck, I see the TC reach stall RPM...and stay there for several seconds...whenever I try to start up a 10 percent or greater grade from a dead stop. The truck does eventually move....but the acceleration is glacially slow... at WOT it takes 10 to 20 seconds just to get up to 20 mph . You sea level types could probably somewhat duplicate my findings by (1) removing 4 spark plugs, (2) loading the bed with a thousand pounds or so of cargo, and (3) from a dead stop, try climbing the steepest hill in your area.
Since I'm getting a 2200 RPM stall with half or less the torque you guys have...and reports by various folk indicate that even full power trucks also have about a 2000 to 2500 RPM stall, I'd say stall speed is much more correlated to throttle postion and transmission turbine RPM than to engine torque.
Flow Master Dual Exhaust
On a honkin' big 454 cu in motor, 3 inch (or even larger) dual pipes are a perfect size for low end torque. But we're working with a pretty small 285 cu in engine...and the ideal dual pipe size (well under 2 inches) just isn't, well, very "manly". 
And if it isn't "manly" in appearance, it's simply not going to sell at all well...no matter what the dyno results are. 
, the smart approach is to simply replace the muffler (and muffler only) and leave the rest of the piping alone at the smartly engineered 2 and 3/8 inch diameter single pipe. No it won't look "tough" but it can sound pretty tough (if you use a muffler designed for a a "full" sound with broad appeal (e.g. Flowmaster)) or it can be pretty quiet but very free flowing for purposes like towing (e.g. by using the biggest Gibson muffler).
Your choice, your money. 
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