Take the GT, paint it lime green, then put flame and bullet hole decals all over it, along with a massive red R on the hood.
You'll make peoples heads explode.
My serious advice, however, would be stay with your PJ and Shelby. They're very nice cars- I like them better than the GT- and honestly, nobody needs a supercar. One wreck and you'd be screwed. Hell, if it were me, I'd just get the PJ, paint it black, and put the rest of the money in the bank.