I have been searching the threads and also looking for articles and maybe I missed it, so if I did, please drop the thread, i put it in this thread topic cause I figured more people would see it, thus someone might know the answer, so no hate if one of the mods moves it

but my question is how do the differences in pipe diameter effect different engine setups (F/I or N/A)?????

I guess to be more specific, This isn't a "which headers are better in your opinion" noob question, rather what kinda pipe diameters, lower collecter, as well as bend design should I be looking for???

Example: Nismo R-tune headers
- 1.625" primary tube stepped up to 1.750" diameter
- 2.25" collector
- Heavy-duty 3/8" flange
http://www.vividracing.com/catalog/n...z-p-19791.html

Ive owned a set of Borlas for the past year and heard all about them, and I can't say I was impressed with this product, and probably would have gone with another design and just might in the near future swap out, but insted of asking "which brand is should I go with"?? because I seen tons of people just say what they have, but rather what kinda numbers/ diameters/bend designs would be optimum for an NA set up as well as FI set ups for others who might have the same questions???

I think alot of noobs ask "what brand they should go with". but nobody ever really answers with "WHY they should use 'X-brand' headers" with any numbers.

Oh forgot to add that I understand also HR and DE engines being different so most likley the same dimensions wouldn't be compatable.

 

On an NA setup, its really impossible to talk about headers without also talking about cams and intake manifolds...which is why there is no 'best' out there for everyone

 

so ok... assume then a VQ (HR or DE) has all the proper bolt on's(intake/exhaust) ,valve train improvements, even ECU work, a tuned engine under 310rwhp mark,... what kinda measurements in diameter are compatible

 

first, it matters if its an HR or DE, and it also matters if its a revup or not

there are far too many details needed to draw any significant conclusions - it is all totally dependant upon the exact setup, not a generic setup

 

ok,...so then its a case by case selection then.

Thanks for the replys. ....still kinda fustrating tho!!!