theres a thread floating around here somewhere about seafoam engine cleaner. you pour some in the oil, some in the gas tank, and suck some up from a vacuum line. one thing to remember is the difference felt by these cleaners depends how "dirty" your engine is in the first place. i second the BG44K stuff, i've always used it and it seems to work pretty well.
In my hunble opinion don't use injector cleaners... there is to much to risk. Pull them out and have them cleaned by a reputable shop like RC Engineering. One bad injector can lead to a fried piston!!! If you don't push your injectors then maybe this additive/cleaner will work :dunno: