a better aftermarket??? are you kidding? John Cooper Works makes every damned part you can think of for that car. I was very impressed w/ the Cooper S i drove (this coming from a road course racer) , it handles awesome and was pretty damned quick. It could use a lil more HP to make it more fun on the track, and i am still considering getting one as a daily driver and leave the 7 parked except for track use.
My opinion?? Cooper S kicks ass