"huge" is a pretty strong word. I wouldnt say huge at all. The performace is mildly-to-hardly felt. Top end basically. THe absolute one thing im thankful for is that this piggy (in the right hands) can give you the abilitly to tune your car for a higher octane if you'd like. By that same token you can also modify your fuel map if you ever get other performance parts and such... Since i made this thread i've re-tuned my car for 91 octane and still get at least 415+ miles on my 08 5speed. Worth every penny.