The primary difference of an H-pipe and an X-pipe is where the power gain comes from. The X-pipe is going to give you a power difference at higher speeds, whereas the H-pipe will give you more on the low end. Also, the x-pipe tends to be a louder and raspier sound. The H-pipe has a significantly quieter tone at idle than the x-pipe, but does contribute to what many consider a, "classic muscle car tone." There is none greater than the other, it simply depends upon your personal preference. Hope this helps!