I have a 2003 GT and I purchased the American Thunder system from AM last year. It's too damn quiet for my liking. Anyway, I'm not sure if I should just purchase a different catback exhaust system, or try adding an aftermarket H/X pipe? I hate the idea of spending another $500+ on a new catback system, but I'm just not sure if an aftermarket X/H pipe will be loud enough? Also, I'm curious if a catted X/H would be much louder than the factory pipe?
Throw on a off road h or x pipe whichever you prefer and it will wake it up big time!. Night and Day difference bud. Off road h/x pipes aren't expensive. If you are a really tight budget look at brands like BBK, Pypes, Summit Racing ( they make their own ), and Jba i have seen for good deals as well. Cats will tone down the sound a lot. Check out utube for comparisons and you'll be amazed at how much of a difference a off road mid pipe will make!
If you'd like I can post a video of my set up. I love my o/r x-pipe despite the installation being a pain in the butt. It can be a nuisance sometimes like if you wanna talk on your phone and drive but other than that I've got nothing but compliments from my coworkers and friends.