What size exhaust pipe to use?

[playboycarti]

In the process of making a custom exhaust for my 3v and my question is simple. The collector for my LT headers (bbk) seems to be 3’. Do I need to use 3’ pipe all the way back or is 2.5’ (as seen in photo) good to use?

 

[AHaze]

How much power are you planning on making? 2.5" is probably fine up to the point where you would need a built short block but if you're close to that point it may be worth stepping up to 3" while you're at it.
FWIW, the early S197 GT500s only had 2.5" and I'm pretty sure they only stepped it up to 2.75" on the later ones.

 

[playboycarti]

Mid 300’s so it sounds like I will be good! Thanks!

 

[Dino Dino Bambino]

How much power are you planning on making? 2.5" is probably fine up to the point where you would need a built short block but if you're close to that point it may be worth stepping up to 3" while you're at it.
FWIW, the early S197 GT500s only had 2.5" and I'm pretty sure they only stepped it up to 2.75" on the later ones.

A dual 2.5" system will support up to 500hp without restriction, while a dual 3" system will support up to 700hp.

https://www.angelfire.com/my/fan/Exhaust_Pipe_Size.htm

Mid 300’s so it sounds like I will be good! Thanks!

Therefore a dual 2.5" system would be plenty big enough.