Hello, new here. I am doing some research before I buy a mini and am wondering how much power you could gain from the pullies from M7 tuning. The one is 16% smaller and the other is 2% bigger.

 

The JCW car uses a 14.7 % pulley the smaller pulleys overdrive the supercharger
They are available up to 20% but they require additional mods to support the boost
There are numerous other "makers" other then M7 tuning.

There are also UNDERDRIVE pulleys
for the accessories that causes slower rotation (and lightened) less drag

 

Yea, I have seen that others make smaller ones, the smallest I have seen is 19%. I was just wondering if the combination of the two M7 pullies is a good choice. Also, What is the highest boost one of these coopers can handle/make.