To me, the H-pipe sounds much better than the X-pipe. The X-pipe can sound really raspy, especially with flowmasters. The x-pipe actually won't really give you much more power than the h-pipe until you're on the high side of the 300 horsepower mark. Nevertheless I like the X-pipe. To me it really depends on how much the price difference is. You might get the 5 horsepower you mentioned if you've got at least 350 horsepower.