I"m with Valk on this one, it was the best money I spent on my crossfire. My wife putts around town from time to time in it and I would get in it and it would act like a 4 banger from time to time. I also noticed that even if I put the pedal to floor it would sometimes take off like a turtle. Since I installed the sprint booster it runs like a sports car like it should. I really don't care how it works but that it does improve the fun factor in my car. If I had to do it again I'd buy it in a heart beat.