I drove a P90DL to get a sense for the speed, and after doing so opted not to do it with my P85D (Insane). The car is "insanely" quick enough already, and since I try to stay around 5mph over the speed limit around town (the car is flashy, no warnings in my future from cops), the extra few tenths wasn't worth it to me. $5000 buys a lot of tires, and my 21s are going fast.