Hi Paul, The Sprint Booster makes a noticeably quicker throttle response and is great if you don't have a tune. If you get the Eurocharged ECU tune however, you won't need the Sprint Booster as the tune adjusts the throttle response. Having both is just too much . . . that's why I took mine off . . . the throttle response was TOO sensitive after getting the ECU tune . . . The car became difficult to drive because the slighted pressure on the peddle caused the car to lurch forward and then you'd compensate by letting off the peddle and so forth. It was like someone learning to drive a stick shift for the first time!