folks, i'm about to replace my supercharger pulley on my 04 R53 for a small pulley but want to know of any drawbacks before I do it. I've heard that it'll give me an instant 20 hp to my MCS, please varify. Also, is there different sizes I can pick from or just one size? Please advice.

 

15% is recommended if your not planning on getting tuned or running atleast the jcw injectors, or you can do 17% or 19% or you could also find the jcw 13% if you dont want to do alot.draw backs your going to use more gas just because you'll be pushing the pedal down harder and mor often

 

A pulley upgrade is your best bang for the buck! You'll love it!!

 

The pulley is bar far the best bang for the buck but your expectations are a bit high. The rule of thumb in most cases is 15 ft lbs of torque and 15 hp give or take a few . You will certainly notice the change in any event . It's a good mod, go for it .

Randy
M7 tuning