I know 3" is ideal for boost but with my power goals of 230-240 I've read that 3" will be overkill and while it will help my spool times, that's not a worry at all since I'll be running an 18g. My question is...currently I have a straight through 2.25" exhaust to an es tuning muffler, will I make a noticeable difference in power with a 2.5" catback? Thanks.

 

where is everyone getting this information that 3" exhaust is recommended for boosted vehicles?

3" exhaust is overkill for a street vehicle. 2.5" is plenty. dont waste your money on anything bigger than 2.5"

 

I know that is overkill, that's why I said it in my post. My question is how noticable the difference between 2.25 and 2.5" piping will be.

 

if your running low boost you wont notice a difference.

 

10psi on an 18g so pretty low. I think I've decided I'm gonna keep the 2.25" since its my daily, and then run an e-cutout at the end of my dp.

 

you should be fine.