Jack21,
I bought the BAER units. They were the biggest available at the time. I was already committed to 17" wheels.
The ones I bought have the 13" rotor, came with the PBR calipers and pads (same as the late Mustang Cobra), aluminum hubs and caliper brackets. I also went for the aluminum hats which save somewhere around 6(?) lbs per side over the solid rotors.
The total cost was about $1200.
The hubs reduce the front track by 0.3" per side, 0.6" if I recall correctly.
One of the reasons I went this way was BAER's statement that Bondurant's driving school uses the same front brakes on their Mustangs. I called and asked, and they said they did, and had no particular problems.
Hope this helps,
Tom
PS: If I didn't already have the calipers, I'd be tempted to ask BAER if the Cobra calipers would interchange - you know, the ones that say "COBRA" right on the caliper
