In an MTX it advances the timing and optimizes the air/fuel ratio.
In an ATX, it does all of the above and also remaps the transmission shift points.
It also raises/removes the top speed limiter and raises the rev limiter on both ATX and MTX equipped vehicles.
Just so you know, all of the following do the same basic thing: SuperChip, JET Chip, Venom400 Module and WeaponR PowerECU.
Mike