a piggy back computer to increase fuel and timing for more safer power gains. works with the stock computer. this is made by hksand has a 86-88 rx7 t2 harness. it contains different fuel maps by the change of a dial. if your running more boost and mods this will keep your engine safer by adding more fuel so you don't lean out. if you want to keep your stock computer without going to a stand alone system this is your ticket. it just plugs in between your computer and engine harness.