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Forced Induction SystemsDetailed discussions regarding cold-air intake systens, superchargers, turbo chargers, and other induction systems for your vehicle.
This is a discussion thread titled "Doug Thorley 5.7L Headers", within the Forced Induction Systems forum, part of the Technical & Vehicle Assistance Forums category.
So from what I'm reading, it is 304, even though you haven't said "It is 304 stainless."
However, is the FACTORY warranty affected at all?
-rockstate
304 is what I said we use on our motor cycle exhaust where the tubes are raw, but with our headers we use mild steel with ceramic coating. If you have any problems with corrosion, then you return it. Its part of our Limited Lifetime Warranty. I have not had any returns on them or seen any problems. We also use this same material on the headers for sandrails that see temperatures way above what any normal vehicle would see.
As for warranty I am not 100% sure. I don't think so, because it is after the engine and does not mess with the catalytic converters. But I will call my local dearship. Its always tough with dealers because each one is so different. When we got our EO numbers the truck went to a local dealer and had no problems. But it is something to be researched.
304 is what I said we use on our motor cycle exhaust where the tubes are raw, but with our headers we use mild steel with ceramic coating. If you have any problems with corrosion, then you return it. Its part of our Limited Lifetime Warranty. I have not had any returns on them or seen any problems. We also use this same material on the headers for sandrails that see temperatures way above what any normal vehicle would see.
As for warranty I am not 100% sure. I don't think so, because it is after the engine and does not mess with the catalytic converters. But I will call my local dearship. Its always tough with dealers because each one is so different. When we got our EO numbers the truck went to a local dealer and had no problems. But it is something to be researched.
Ahh thanks for the info! Sometimes it's hard to decipher stuff like that when it could go either way.
I just got off the phone with a dealership in my area and he basically said stuff about the Magnusson Moss Act. I'm familiar with that so I asked him how often headers actually cause problems and he wasn't sure.
Mild steel with the heat coating is better. the stainless stuff doesn't weld good and the heat expansion of the tig weld is different than the header tubing...crack city.
the DT tri-Y mild steel coated header is one of the few that won't crack on jeep 4 liter straight sixes (including stock). I'd buy this right now if i had the money burning a hole in my pocket.
One question... stock muffler on those dyno pulls?
What is the best exhust to use with these?? Does one help over another??
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2007 Tundra 5.7 Double cab Silver TRD sideboards line-x Bluetooth gotta love these trucks
2007 BMW 650cic Black Tan Leather, heads-up display, lojack, polished rims, unreal car
So that would be fresh air added to the exhaust? Which would come from the intake... so would blocking that give any performance?
NO! It just dilutes and cools the outgoing exhaust gases. They do this little trick on my Yamaha WR450F motorcycle. It's only purpose it serves on my bike, is, better exhaust pollution numbers at the tail pipe!
So that would be fresh air added to the exhaust? Which would come from the intake... so would blocking that give any performance?
For the dyno pulls that we did, everything else is stock. No exhaust no intake, no nothing.
MPG, since they are so new we don't really have much data on, but generally speaking its 1-3mpg, and how much you keep your foot out of it!!
Intake and exhaust will always help, they go hand in hand when it comes to performance add-ons. I always recommend putting in a drop air filter or intake with a catback to get the best results with the headers.
And yes, the gentlemen that stated mild steel thermal properties are much better suited for this application. Are Jeep headers are quite well known as well as our small block and many other truck applications.
And also, to clarify about any possible group buys. At this time if there are any group buys they will be through URD USA. If you need any other information regarding ordering contact them at - Underdog Racing Development
So you are saying that model 409 is better than model 304 ??????
Sorry about that, couldn't help myself. I've heard nothing but good things about this brand. If I had the extra $ for mods on my truck, these would definately be included.
Ok..... I ordered the darn things! I did ask if they were "ceramic coated" in my order. If they are not, I asked how much moore moo-la that would cost? I have hear that "ceramic coating" is a good thing....... or if not, how about that "thermal wrap" crap?
Lifetime warranty doesn't cover removal/install if (when) the coating goes to pot. I would never take the time to install mild steel headers, coated or not, into a 5.7 Tundra. Let me tell you, it's not an easy task to work around those gigantic heads on a 5.7 Go ahead and take a look on TIS at how hard it will be to get at those manifolds - I dare you! Oh, BTW $600 bucks is outrageous for a set of shorty mild steel headers. C'mon guys, at least make them out of 409, or better yet 304 (or 321 )
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2007 Tundra 5.7 4x2 RCSB slate metallic
2005 Corolla - all stock, cause it's the wifes
1986 Mustang GT - the stereo is under the hood
1990 Corolla - cause it was really cheap
Lifetime warranty doesn't cover removal/install if (when) the coating goes to pot. I would never take the time to install mild steel headers, coated or not, into a 5.7 Tundra. Let me tell you, it's not an easy task to work around those gigantic heads on a 5.7 Go ahead and take a look on TIS at how hard it will be to get at those manifolds - I dare you! Oh, BTW $600 bucks is outrageous for a set of shorty mild steel headers. C'mon guys, at least make them out of 409, or better yet 304 (or 321 )
If you are complaining about cost of the headers now at $600 which is far cheaper than any other competitor, which there is not any. But 321 steel will expand and contract differently than the metal on the head and cause leaks, crack welds and jump the cost up A LOT. If you have not seen the raw material cost of stainless lately than you are assuming too much. As I have said before, I'll say it again, other metals are just not suited for the application. So if you think $600 for mild steel now is a lot, make them 321 and see the price up to $900-1000!! Everything will have to be tig welded, and will be much more brittle and susceptible to corrosion. Nothing worth a GOOD amount horsepower will not be easy. This goes for anything. Our headers combined with an intake and exhaust is the best bang for buck horsepower you can get!!
Re: Doug Thorley 5.7L Headers
Go ahead and take a look on TIS at how hard it will be to get at those manifolds - I dare you! Oh, BTW $600 bucks is outrageous for a set of shorty mild steel headers. C'mon guys, at least make them out of 409, or better yet 304 (or 321 
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