Removing the SAI system is pointless. It does not effect engine output, and is only active at cold start up. Removing the SAI provides nothing except CEL ON. Coding the ECU with a different emissions coding, just loosens the control parameters, and allows for wider variation in the emissions as controlled by the 02 sensors and cat efficiency.
Removing the SAI logic and cat heating prevents the ECU from dumping tons of fuel down your bores on every cold start, which in the long run is beneficial to the life of the engine.
It also noticeably reduces fuel consumption if you are doing a lot of short trips.
Other than that, the pump and kombi valves tend to fail and their replacement is expensive.
