i have an 04 JCW and am considering going to a 15% pulley. How is performance affected ? how about gas mileage ? thanks.

 

You'll notice a bit quicker low end power and a few extra hp at the top. IMHO it's not a mod worth doing on a JCW.

I'm still on the stock JCW and will keep it even after upgrading the head. After a while, over-spinning the supercharger just makes heat....

 

^^what he said

People that have changed them though will tell you they like it. It will basically just shift your torque curve down a bit.

I will tell you though that a smaller pulley is not necessary to make good power....im at 231whp on the stock JCW pulley and the mods in my sig. I know of another GP with head/cam/header thats at 265+whp on stock JCW pulley.

 

stock JCW pulleys are already at like 14%, so, your wasting your $$.

Go big. go for the 17%. its AWESOME. really makes the SC screeeeaaammm

Gas mileage, about the same if you ask me. you may drop like, 1mpg? thats all i think i lost... depends on how you drive it of course. I get 25 city, 28-30 hwy still.

 

The JCW pulley is about a 13% pulley. Most customers that have changed it out have gone to a 17% pulley. You'll gain more low end.

 

I have to agree, if your going to change a JCW pulley, you really need to step up to a 17% to notice a big difference. Might want to run meth though to keep the charge cool.

 

I think your driving style, and how you use the car should dictate if you stick with stock or go to the 17%...
if you run lots of high rpms (auto-x), bump the rev limiter, etc, the stock will likely make more power...but if you do more intown driving, and the extra tq at a lower rpm is nice, you will love the 17%.
it is great if you live in an area with 92 octane....

 

I kept the JCW pulley and installed a 2% ATI Crank Pulley to replace the failure prone OEM unit.
http://www.waymotorworks.com/super-d...ulley-r53.html