Deuce228 is right. The Police Interceptors have heavy duty everything and coolers for all the hot parts like the tranny, steering, and an external oil cooler. I believe it also has the front lip that directs air to the front brakes. Try putting some headers, catback exhaust, cold-air intake, and free-flow cats. You car should easily handles these power upgrades. Or just start with a cold-air intake for immediately noticeble power. Considering the weight of the car, your tranny should be good for about 400lb/ft of torque.
PS - most police cars are VERY well maintained mechanically
PS - most police cars are VERY well maintained mechanically