How much power can you get on stock exhaust with turbo?
 

I'm about to chuck a gtx2867r snail on my beast.

I'd love to know how much power I can push through the stock exhaust/pipes and what psi as I need to pass an emissions test. :(. I'm looking to get 280-300hp

Ideally I'd want 3" all the way back.

I still have a stock catback on mine. 3" to it though. I'm at 277 whp on 10psi with a GT2871r. I know it's a restriction. Full stock exhaust would be awful.

I see a lot of people from Australia worrying about not passing emission test.
Have you guys ever thought about just throwing the stock catback onto the car for inspection? :P that way you can still mod the car as you wish to.

Catbacks are not illegal. They pass CARB so they likely pass everywhere.

The catback has no cats in it (thus the term catback) and zero impact on emissions. Putting it back on for emission testing would do nothing.

Legal for emissions but possibly not legal for noise depending on where you are and what catback you run.

(I know the question said turbo but....) I'm running fully stock exhaust with the harrop supercharger. 240whp on a hot dyno day. It is a restriction and to be on the safe side my tuner has dialed back some timing at the top of the rev range.

I want to sort it out, but it seems to be insanely expensive to get a decent forced induction header (~1.5k), and I am worried about how loud it will be with the full exhaust done.

It has negligible impact on emissions--not no impact.

The catback is still not illegal if it is too loud. Someone just gets a noise violation ticket like having a loud party--parties aren't illegal. It just needs to be modified to have a silencer at the tip. Many catbacks come with a silencer if they are higher than a certain decible.

So small an impact that "no" is an accurate word. From the cats back it is just pipe and baffles that do virtually nothing to the emissions. Putting it back on for testing would be a complete and total waste of time and to say to do it is just silly.

Getting a ticket is the very definition of something that is illegal. No, parties are not illegal, but the noise that they can create is.

Yes you can put a tip on it or as I clearly said the noise depends on the catback you chose. They are not all noisy by any stretch.

ops! I was totally heading the wrong direction on my previous post.
OP could keep the stock front pipe since it would be the only cat left when turbo and run a aftermarket catback(for more power gains)?

Yeah it is. But it still increases emmissions.


Again, noise violations are illegal. Catbacks are CARB exempt and legal. Honking your horn in a non-emergency is illegal and can also be a noise violation but horns are not illegal. The silencer componet of street exhausts are part of the system. Without it those exhausts are often advertised as track only.

Wrong question, better to say how much will it nerf your turbo setup lol

To pass emission you need 2 cats and ask the tuner to tune to pass emissions