I bought my Mini used just over a year ago so I did not have or uninstall the stock sc pulley and didn't install the wmw 17% that was on there. I did just order a new one on amazon since I could get it Monday (mini is my only car) it's by cravenspeed so hopefully that's a decent brand. And hope that it does not come off again not really sure how but now I don't know if I can get the pulley on tight enough since the input shaft has been worn some now..

 

CravenSpeed is a good brand, so you shouldn't have issues there.
You'll just have to take extra care and pay close attention when mounting, hopefully if there is a problem it will be evident up front.
Good Luck

 

And Thanks a lot everyone even though it was something kind of silly and simple (relively) I get some great input and what to watch for since im not an extreme long time mini owner.

 

There are almost 85,000 threads here on the Gen1 Mini. You need to know something about your car, between those threads, the members and vendors the chances are you will find/get the answer.