While the engines on cop cars aren't really upgraded froma regular Crown Vic, the suspensions are. The big thing is that the anti-sway bars are much bigger and thicker. That alone makes a big difference. Once I buy mine, if I like it, I'm going to upgrade the exhaust, rims and tires, and ... Well ...that's about it. I might buy a different springs to lower it just a little bit. but any performance mods you think about doing to the engine that would really make a difference or just too expensive. Like superchargers or dumb stuff like that. No sense in throwing that kind of money at a cheap car.