Re: x-pipe

X-pipes create more horsepower and torque in the mid to upper RPM ranges than the H-pipe. They also have a rapier sound than the H-pipe. H-pipes create more horsepower and torque in the low to mid RPM ranges than the X-pipe and have a deeper rumbling sound than the X-pipe. Depends what you want. You get out of the hole quicker with the H-pipe, but the X-pipe will help out with the gutless top-end of the 4.6L. You get better sound with the H-pipe IMO as well. Personally I went with the H-pipe because on the street it is all about acceleration and not about higher top speeds...and I like the sound better.