I'm trying to find out how much HP one can make with a stock catback (and test pipe). I own a Js 70RS, but don't want to use it if I don't have to because its extremely "droney". I was thinking it would quiet down with a turbo setup and would only use it in that case. Has anyone found out how much the stock catback is rated for both for turbo and supercharger applications?

 

Was fine for me at 14psi on SOS SC kit

 

Your question doesn't really make sense. "X" exhaust isn't rated at a set HP. Your only measure is going to be how much one is restricting you. For example, the first reply here. Maybe he got to his HP goal on a stock exhaust, does that still mean it isn't a restriction? Would he have gained power from swapping exhaust?

 

I made 401 with stock exhaust and 70mm tp

 

Yeah I've also seen some people make a bit over 400whp supercharged with TP and stock exhaust.

 

I can't speak for stock, but I ran a Q300 before boost and it was fking unbearable. I kept the q300 when I went turbo and it sounds completely different, WAY better.

 

Good to know that turbo quiets the exhaust a bit.

To clarify my question, I'm looking at what the highest HP someone has made with stock exhaust and a test pipe. I understand that exhausts are not rated for HP values, although I do know that stock is relatively restrictive.

 

If you have enough boost to force flow, you can make a lot of power on a restrictive set up. Problem is, there is a point where your EGT climbs higher and higher until you melt the engine down. You need to be able to expel those gasses efficiently to keep the engine working at least as possible. The stock cat back isn't as bad as you think, but yeah there is a point where it really starts holding you back on good efficient safe power. Id say if your planning on making much north of 400whp, to just plan on ditching it. Cat delete or HFC is what's going to make the most difference first.

 

I'm sure I have seen countless amount of people in the upper 400s with the stock exhaust. As long as you have a test pipe the stock catback exhaust should not be a huge issue until over 500whp. At the 400ish who level I would think a full 3inch exhaust would be good for about 10-15whp over the stock catback exhaust.

 

This makes sense to me, I'd love to keep the stock cat back if possible. Thanks.