you can stil use the 1.8 ecu.you can't use the 2.0 ecu as the sensors are different or something. The 2.0 will fit, you can use your gearbox. What you will need to do tho is get a power boost valve or get a unichip so the fueling can be set up. a fair few people have done it on http://www.rs20004x4.com/test theres a fair bit of info lurking around there somewhere about dropping a 2.0 in to a 1.8 or 1.6