When I got it done I took the car out for a drive and was flooring it, there is a differece but not that much, when I got home I wasnt that impressed, thought to myself that It didnt seem to do much!!. Then I stood with my foot in the door and gave it a rev and it sounded mental, then as I said, had to get my brother to take it for a drive whilst I stood and listened! Then I was massively impressed!!!!! It sounds truly epic popping and banging through the gears!!! Best £30 I have ever spent!!!