Throttle controllers don't work, I have tried one. The throttle restriction is built into the ecu, and occurs when the brake signal pin is energised. It also latches for 3 seconds after the brake is released. You need to cut the brake signal wire to get 100% throttle, but this will eventually throw a CEL so you need to wire a switch across the wires also.
Do a search, there are a few threads on the throttle restriction and brake cut mod. Highly recommended.