they are not laggy at all!! I never got a chance to run the sport 600s without them! And i still wouldnt recomend putting them on without some manis :) This was done at 25 psi since i took the devils Zs advice :) On a dynojet the numbers would have been around 615 rwhp and 530 torque, Since my buddies corvette dynoed 405 rwhp on a dynojet, and 358 on a mustang :)