The ABS on the MKIV Supras is handled by a standalone ECU down behind the radio. The engine ecu change shouldn't affect the ABS operation. There is a MKIV owned by a Motec dealer here in the UK running standalone M800 using fly by wire throttle and the VVTi system. His car was used my Motec UK to chart the FBW parameters and VVTi parameters of the stock ecu. I assume your car is a manual? If it's an auto I have not heard of anyone using a Motec to control the throttle closure and maybe retard functions on gear changes. The AEM plug and pray ecu attempted to do this, but a lot of damaged auto boxes suggested something was never quite sorted. Most auto MKIV's over here use a piggy back set up, running the stock ecu to control the auto box functions and the aftermarket one to just run the baic engine parameters. Hope this helps.