The big thing is IF you can get it to launch the same. My car and every other WRX I've seen with a lightened flywheel has fallen on its face when trying to launch. With no wheel spin to get rid of some of the energy produced in the drivetrain and loss of rotating mass from the lighter flywheel it just bogs bad off the mine. That's something you might want to think about before doing it, I'm going to be pulling mine out soon and going back to the stock flywheel.