I'm having the pulley done. but stay away from the flying wheel. It will give you a bit more noise on everyday driving. If you would like to take it to the track a lot or do autocross. you can do that, it gives you better performance.
Do not worry about the trans system too much. there are not mouch you can do about it except spend big money on it. If you really plan to spend some money on the car. Spend it on wheel, intake, pulley(15%/17%, too hot for 19% in HK) sway bar, short shifter or exaust.
It will give you so much hp than you can imagine on the mini.
Good luck.
Ohh.. dont forget, turn off the
DSC!