In a nutshell:
Hpipe = more low end torque
Xpipe = more power up top
Hpipe is generally louder than an Xpipe
If you go offroad you'll need MIL eliminators
try
www.dallasmustang.com
If you go hiflow (2 cats) your CE should not come on and should still be street legal.
I'm going with BBK. From what i've heard, their fit and finish is the best.
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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
30 Years & 30 inches apart in the driveway!