I have an 04 S since new. I have done many mods myself, supercharger compressor pulley, crank pulley (because the vibration dampener came apart,) Unichip ECU piggyback, accel pedal delay reducer, exhaust, air intake. All this makes the car quite peppy. The braking part is the REAL problem. We put in on the track, a few times, for Friday at the Track days and cooked the brakes severely. It cost me new pads(replaced with Hawks), new rotors, metal braided lines all the way around and silicon high temp fluid and we fabricated air ducting to the front rotors. I even had to replace the front hubs as the grease was running out of the bearings. Subsequently, in order to bleed the brakes properly and activate the ABS, I purchase the computer based scan tool that allows you to operate the ABS on the shop floor. All this being said, I missed one item that is critical, the Speed Sensors for the front wheels. They apparently got cooked too and after all the preceeding work we never quite got the front brakes to operated with full authority. Incorrect Speed Sensor reading throw the ABS controller off.

This note is just advice from personal experience, the stock brakes in the Mini S are incapable of withstanding the additional horsepower the aftermarket has allowed us pull out of this tiny 1.6 LTR engine. If you are thinking of putting you Mini on the track or Autocross, I would say "think BRAKE UPGRADE" first.