[acammer]

You want some form of cross-over, whether it be an H or an X. Power wise you find a very in-significant difference between the two. The noise, however, is very different. The factory H pipe produces (to me) a very pleasant "lublublub" typical to a muscle/American v8. It has that nice pulse typically associated with an "old-school" sound. When you're hard in the gas and the revs are up it has a nice growl to it.

The X pipe pretty much completely loses that "lublublub" pulse that you get with an H pipe, it sounds much smoother, a little more exotic, definitely less "muscle car". And when you stand in the gas they really wail, it's a bit more violent, almost shredding sounding scream.

I actually prefer the H-pipe sound myself - alas the previous owner spend all sorts of money on this nice American Racing X-Pipe, and I can't bring myself to remove it. It's a trade-off really, driving around easy the H-pipe shines for beautiful noise, however it's hard to beat the scream of the X-pipe at full song.