How noticible a change with upgraded exhaust?

For those that have installed upgraded exhaust/cats and how noticeable a performance impact does it make? Which exhaust system do members recommend the most?

Oooooh Ooooh Ooooh do I get to answer this one? I'm assuming you've already searched the forum and read past topic threads on exhausts where several have been discussed in detail right? I'm also assuming that you've read all of the aftermarket exhaust install articles in the Articles section as well correct? First question: Impact to performance - Depends on whether you go full exhaust or catback only and which brand you choose. There are at least a couple of brands that can get you 20-21hp gain at the rear wheels for a full system which is certainly noticeable. Second question: Most recommended? That's easy, the one that best meets YOUR criteria for selecting and installing an exhaust. If you value say loudness over everything else, that will lead you to a difference choice than say the one with the most HP gain, or the one that is quietest around town, or the one that weighs the least, or the one that is the shiniest. Without knowing YOUR criteria we wouldn't know what to recommend.

I have a cat back and definitely noticed it. Sounds better and has better throttle response. I'm guessing most will offer a significant weight loss over the stock unit as well. I can't remember if I asked but I think it would be a great idea to have a sticky with sound clips and info on the different systems. There are definitely a few to choose from now. I agree with Kman though, personal preference and what you want from the upgrade will help steer you to the right one.

BTW Kman is testing a new uber cool system any day now.

Thanks for the responses. I would want the one that weighs the least and has the most hp gain I did read many of the threads, but there are so many it is hard to determine which way to go.

From a pure weight vs. HP gained ratio I can't think of anything that outdoes the AWE exhaust at the moment, although they only offer catback, you'd still have to marry it up to someone else's headers like Milltek, Fabspeed, Capristo, etc. The AWE cans are pretty small and thus certainly weigh less than stock and are similar to other smaller can exhausts and have have a proven 3rd party dyno breakdown on their performance. Some don't like the look of the cans though since they are squarish vs. roundish for almost all other systems out there. If someone knows of a lighter system that produces more hp I'd love to see/test it.

Thanks for the info. Out of curiousity which one is producing the most horsepower?

AFAIK the complete Milltek system has produced the most hp gain of any system independently tested, but not every system has been tested yet. Milltek is also working out their header issues at the moment with the cat failures that have happened.

What is the maximum gain claimed from an aftermarket exhaust rear section only, with stock headers still in place? Thanks for your help.

David, Welcome to the site, I've been awaiting your arrival. Stock manifolds but with aftermarket catback exhaust the max gain I've seen is 12hp I think, I'd have to go back and check some figures, the range I believe is 8-12hp gain for most systems I've tested, but again I'd have to go back and look at some figures to see. I know there are some dyno charts in the AWE article in the Articles section that shows their catback system with both the factory manifolds as well as the Milltek headers.

Thanks so much for the kind words and valuable info. We are having a ton of fun with this exhaust development.

Best not to ask Kman that because he has to remain "neutral" these days.

If you ever have time, it would probably be useful to have a chart listing pros and cons of each system. But I suppose the pros and cons are very subjective?

There is an exhaust chart in the FAQ currently, although it probably needs a little updating, have you checked it out?

No I did not see it. I will check it out. Thanks!