There are many piggy's, one of the best is the Gretty-E manage piggy, then there are others like the Apexi which I currenty have on my car that is running nos now. Many others as well. David actually made me aware of this when I was pushing towards a stand alone. Check it out before you spend the $, you can save easily half the money and end up with close to if not the same results with piggyback unit.