Quote Originally Posted by GTPpower View Post
If you want that much power, you should probably get the XPZ.

Stock rockers will give you more lift with higher lift cams than a set of roller 1.7's.
I would rather have less lift and wear/friction on the valvetrain with roller rockers than the stock ones.

Quote Originally Posted by darkhorizon View Post
xpz has proven to make the most power consistantly... the IS3 is not setup for a m90 at all.
I would be more inclined to the XPZ if I could find more information on it like the specs that arent listed on their website. Why isnt the IS3 not for an m90 car? The IS4 is supposed to be for bigger blower cars