What is the difference between an FM I and an FM II in a 1999-04 car?
The FM II takes the FM I setup and adds an intercooler and electronic boost control. The piggyback is pre-programmed for the FM I and the FM II includes a programming keypad. Otherwise, they use the same turbo, fuel and timing control and as many of the same intake pipes as possible. The FM I will operate at approximately 6 psi of boost while the FM II is typcially run at 9 psi on a stock engine.
