I too have gone to the dark side, well actually maybe just stepped into the shadows as I've picked up a used 1999 Mustang GT upgraded to a Bullitt motor and trans and fully outfitted with the Cobra R wing, front end etc. Previous owner upgraded a bunch of stuff for open track events (coilovers, caster plates, big brakes, chassis stiffners, 3.73 w/Auburn, oil cooler, Canton pan, NT-05's, etc). I bought this car so my kids can learn to drive a stick and do autocrosses and open track events. Parts and replacement stuff for a Mustang are so cheap...one new Viper wheel will buy 4 replacment wheels on a Mustang.
Apparently the new Mustang GT500 has been derated to drop the power down to 650 hp....kind of scary to think what a pulley, tune and exhaust will get you with a brand new car. For people that like to modify or add a lot of crap to their cars, the Mustang plateform can be beat.
Let us know an honest opinion of your new ride, enjoy it.
Cheers,
George