2.5in to 3in exhaust

[Talon4ever]

I currently have a full 2.5in exhaust. (Bushur Downpipe, no cat, and custom mandrel bent cat-back with 2.5in muffler) I was wondering if I should make the cat-back into 3in. So I would have a 2.5in downpipe then go into a 3in cat-back. Does this make sense? Would I get more top-end power since there would be less back-pressure or is this just a waist of money. I am still on the 14b and I don't think I will be able to upgrade since I don't have the money. The only other upgrade I will perform will be the gm maf translator with the blow-thru set-up. Any comments or suggestions?

 

[EvolvingGST]

if your not gonna upgrade then NO... just fabricate a connection between the 2 like me... it turns out they make piping smaller for exhaust for us FWD people... I still love my 3 in DP w/o cat to my 2.5 cat... its ok for me... and if you do upgrade you might not go like super huge turbo and stay with a big 16g so it will all be ok... just stay as is for now.

 

[midnght]

You are fine the way you are. You are not going to see sig. gains from going 2.5 to 3. Especailly if you are going to have a 2.5 before the 3 inch.

Remember this....

You can only flow your what your smallest section will allow.


Spend that $400 on something more needed.

 

[Talon4ever]

Thanks for the info. Even though I am not going to upgrade can I still get more power from the 14b by going to 3in? Just curious because I can get a custom 3in cat-back for 85 bucks.

O yeah, I heard somewhere that you can get away with starting out 2.5in and then going 3in because the exhaust gases are still very hot and flow more easily right after the turbo. As the gases cool the flow slows down, so this is why you can open it up to 3in. This is what I heard. Can someone please correct me if I am wrong.

 

[midnght]

If you can get it cheap, then by all means go for it.

If it comes down to a choice in the same $400-$900 range, the 2.5 is more than efficient for your setup.

 

[EvolvingGST]

from what previous post have told me it doesnt really matter for a 2.5 or a 3 inch if you dont plan to make more than I believe it was like 350 whp. You can do a search about it....