The 8.5" wide factory Bullitts have a 6.75" backspace which translates to a 51 mm offset. The high offset is needed to keep the tires tucked under a GP's narrow fenders. The 04 and earlier Mustang offset would be more big brake friendly, but you'd be limited by width.
I have the opposite problem with my Eldo. These 255's on 8.5" Bullitts look skinny tucked away under the fender well "caves". I bet I could run 1.25" spacers and still lower the car some without rolling the fenders (well maybe just a touch up front) but I have room for 315's on 11's under a lowered rear end.... But no budget or purpose for that on the back of a FWD.
There is a good wheel thread here on this forum.
Also, the high offset 05 up Mustang wheels have some models that have spokes that will clear Brembos.
