if you guys get a chance, go to autozone and buy a little red bottle called RXP. this shit is amazing, not for performance but for cleaning out the fuel system. if you go to http://www.rxp.com it explains how it works. i didnt think to much of it, until i had a compression check done and he ask me if i had used any fuel additives. he told me that my cylinder heads ad no evidenvce of any type of carbon or whatever else may be deposited onto them (and i got 135,000 miles). then i remembered putting that stuff into my tank about a month and a half ago. it comes in a 2oz bottle, yeah that is what i thought, but the stuff really worked. i was impressed, and it says that you onlt need to use it once. if it was a scam it would tell you to use it after every fill up right?