headers!
here we go again. first off, almost all production headers are poor.poor design,poor materials,poor performance gains. headers need to be matched to YOUR engine.ie cam,intake,ports,exhaust, compression etc. 99% of headers out there are not equal length or flow.you may gain SOME performance but not as much as with a correct performance header.tony-lindsey-dean of "kingstonmotorsportscars.com" makes some that work for tr6's.he's in england.
if your going to buy headers, buy the best ones for YOUR car that you can.i'm building my own for my tr4.
the only stainless that should be used for headers is 321 stainless.NOT 304!!! i have heard many reports that these crack. (read caroll smiths books-engineer to win-and his others for that matter)you are better off using mild steel and have it ceramic coated inside and out (underhood temps will be less).
people hear "stainless" and think it's better. not true unless it is the RIGHT stainless.
performance gains are in the design and construction(not the material). correct primary lengths and diameter,equal length primaries within 1/2" (measured on the centerline of the tubes), correctly designed collector with both the length and the converging angle and outlet, correct size collector pipe after the converging cone, correct size exhaust and muffler. headers for mufflers are not the same as headers without mufflers. high altitude locations make a difference (your engine takes in less volume of air).
with different lengths primaries, each cylinder has a different tune and this effects the intakes and carb or efi settings required for each cylinder.race headers are not good for the street. you want the correct header. big diameter primary pipes on a street tuned car will probably lose power rather than gain power, so what looks sexy doesn't necessarily work. make the right choice and you will be happy. make the wrong choice because it was cheaper and you live with the consequences.
suggest you go to "headersbyed" web site and read all he has to say and "stahl headers". look at race cars and note the design is equal length.most are custom made.
now look at headers with a more discerning eye.
"headersbyed" did the sizing for me from my design request. i think it will be the best $35 bucks i spent on my car.my headers are designed equal within 1/16" (by me-i am an industrial engineering designer).
rob