You should be able to. Even if the x-pipe is slightly wider to the fit, a competent exhaust shop should have no problem modifying the pipe for you. Of this I am positive. I just put an X on my V6. Just make sure you go to a good exhaust shop, and stay away from Midas

. You do still have the stock cats left over from the original Y still on the car right?
__________________
2005 Mustang Premium V6-Screaming Yellow
"Bee"
Pypes X-Pipe, Custom Dual Flowmaster AT's
K&N FIPK CAI, Cervinis Ram Air Hood, Dual Black Shelby Racing Stripes,Black OEM GT Rear Spoiler;Billit Wheels 17" w/ P-Zero Nero tires, Xenon custom painted side scoops, GT Front Appearance Pkg.
Coming Summer 2010: Custom 93 Octane Race Tune & 4.10 Gears.