My old setup was a mac offroad into flows, and it sounded awesome. After switching to a Dr. Gas X, it sounded awesome. To tell you the truth I don't see that much of a difference. If I had to decide though, I prefer the X-pipe. The car revs up alot higher and sounds ****in brutal at high rpms. I dont hear any trace of "raspiness" or anything of the sort, nor (now that i think about it) did the H sound more "throaty". In my opinion, i think most of the sound comes from whats behind the midpipe, and to a lesser extent, whats in front of it.
Edit: Oh, and power wise, unless your pushin 400 with a stock catted pipe, i dont think you'll feel a huge difference in the ass of your pants. Just my 2 mutha****in cents.