Keeping OEM muffler counter-productive? Options

[Xander_X]

So I'm starting to think about a custom exhaust system. Problem is, I HATE 99% of the mufflers out there and I LOVE the look of the stock GT muffler. Mine is in mint condition as well but my flex pipe is about ready to need replacing. I figured while I was at it, I would replace the entire thing with a high flow exhaust manifold and 2" stainless piping. I'm curious if I were to keep the stock muffler, if it was going to be counter productive to the decrease in back-pressure even though it's at the end-of-the-line.

This isn't really a post to try to find an alternate muffler so much as it is to become more informed of what would happen if the stock muffler was kept.

[Syaoran]

Unless your state is strict on emissions, then you can remove the cat and have no CEL using an O2 sensor cheater (it's a kind of bung that's welded into your exhaust) that keeps your O2 sensor happy so that it doesn't throw CEL. Cats are very restrictive, not even high-flow cats are good. (I used to believe the hype about high-flow cats until I tried it for myself).

No matter how many cells per inch they have, they're still a wall that breaks up exhaust flow. Their flaw is in how they're designed to operate.

Anyways if you MUST use a main cat, a high-flow cat is better than the OEM cat, but it's still a cat is what I'm trying to say.

As for the second cat, you can trick your ECU into believing the mixture "smells" nice.

That is, of course, if you don't have visual inspection.... (gladly where I live they could care less haha)