Anyone have any experience with this??? I gotta 04 S/C gto and Im switching out the pulley, Ive been told to get the meth injection with a 2.6 pulley (9-9.5lbs), but would be fine without it with a 2.75 (7-8lbs). Will that last pound or two really make that much more heat??? Also anyone got any ball park figures on the cost of one???