Pontiac GTO 2004-2006 - h pipe, mandrel tail pipes and stock mufflers?

So, I bought an 04 m6 that has ps long tubes, o/r mids but it still has the stock cat back. I have a bunch of randome mandrel bends and an h pipe in my garage from previous builds (and a welder). How much would I leave on the table if I would stick with the stock mufflers? I also want to keep the stock mufflers because its so nice being able to hear my self think. Let me know what you guys think

The stock system will work fine (and sound great) without leaving much on the table until you bump up the HP quite a bit. Drive it and enjoy.

^^^ I agree. Had a Corsa and went back to the stock cat back. Sounds a lot better and only lost a handful of HP on the dyno when I was around 430rwhp. It flows surprisingly well for a small exhaust.

^^^ I agree. Had a Corsa and went back to the stock cat back. Sounds a lot better and only lost a handful of HP on the dyno when I was around 430rwhp. It flows surprisingly well for a small exhaust.

You're seriously?

I'm running Corsa and would never dream of running another exhaust ever again on any other car.

Very serious. It was an alright sounding exhaust and obviously flowed a little better, but the stock cat back sounds great. Its just not loud enough, IMHO. But it has the best tone of any GTO exhaust I've heard.

Very serious. It was an alright sounding exhaust and obviously flowed a little better, but the stock cat back sounds great. Its just not loud enough, IMHO. But it has the best tone of any GTO exhaust I've heard.

I hear that a lot from the '04 guys. They certainly got it right with that exhaust. They sound great. The '05 GTOs didn't sound nearly as nice.

I'm running Corsa and would never dream of running another exhaust ever again on any other car.


You serious?? Clearly you have not heard a gto with an h pipe and spintechs.