I have an 05 Cooper S with JCW suspension, exhaust, CAI was on its way, until I realized that for an extra $280 I can get the JCW CAI with the injectors and ECU flash. I know there's others then JCW, nut I'm trying to keep in the good graces of my Mini maintainance and warrantee program.

The question: (long winded)
I have exhausted all avenues to realize that the JCW pulley cant be purchase and Dinan will not sell their pulley individually. So I will now take my chances and hope if something happens Mini will not dispute coverage due to an aftermarket pulley.

What brand and size pulley is recommended to increase midrange performance and keep the daily derivability, would live to be able to keep pace (or be quicker) then the full JCW's?

 

You can get pulleys in
11.5% (Forge)
15%
16%
17%
19%
The JCW pulley is 11ish%

 

Dose that mean that the JCW pulley is approximately 11.5% smaller then the stock pulley.

 

Yep

 

Go with a 15% you'll love it.

I carry several different brands and even have our own.
http://www.waymotorworks.com/home.php?cat=327