I am planning on redoing my exhaust from the cats back. I just need to decide if I should go with 2.25 factory size piping or step up to 2.5''? I do plan on going with either the Ford Racing cut and clamp X pipe if I stay with 2.25, or a custom set up X or H set up if I do step up to the 2.5''. I did pick up the magnaflow competition axle backs which are 2.5 inlet that is the only reason I am thinking of stepping up the whole exhaust.

Thanks

 

Have you tuned your car? If you plan on it, and any other engine mods, go 2.5. A 300hp car should have 2.5" exhaust.

 

Yes I am tuned. I agree with you about the 2.5'', my '95 V6 is 2.5'' and that **** motor only puts out like 175HP. I was just wondering if anyone else might have some wisdom, info they can share.

Matthew

 

I had 2.5 on my 00 V6 too. No tune. From my butt dyno, I didn't lose anything down low and had a decent gain in the midrange...

 

the bbk x pipe for their long tubes is 2.5 and im thinking about running 2.5 over axle pipes too since my bassani axle backs have 2.5 inlets. only thing left on mine thats 2.25 is the over axle pipes.

 

I think the best thing is to google around for actual dyno or sound results (depending on what you want to change). Changing the exhaust is common enough that you should be able to find others that have done it.

I doubt that the stock setup (that is cat to axle) is a significant performance bottleneck on this system. The engineers probably got pretty close to the most efficient pipe diameter, and I don't think a tune and cai are enough to significantly alter the volume of exhaust such that a larger diameter pipe is necessary. Also, if you're headers collect to a 2.25" pipe, I don't think you'll see any benefit by increasing the size downstream.

 

supercharged id say theres a benefit, but NA on a true dual exhaust car, I don't think you would see any gain, potentially a tq loss moving to 2.5

 

I def. felt a performance increase when I switched out for 2.5 piping but it was all in the mid to upper power band and this was most realized when I took it off to go with a different setup with 2.25 pipes. No regrets though.

 

Based on the article found at this link, Dual 2 1/2" is plenty for 300 HP. Take a look.

http://www.exhaustvideos.com/faq/how...pipe-diameter/

 

Interesting that the gt500 would be regarded as too small, as it's 670bhp and has 2 3/4" pipes. Interesting read regardless.