The 08 STI ECU uses Immobilizer. It will not work without the other modules present and the keys meant for the system. AS well as the ignition cylinder with antenna. You would have to swap the entire wiring from a donor car. The GR chassis is greatly different than the earlier GD or GC's. It will make the swap extremely difficult. It is much more cost effective to swap in an 04 STI engine and driveline. If you want the dual AVCS you can get an aftermarket controller to control the exhaust cams along with the 04 ECU. You can swap in the abs from an 04 STI as well. You may need to make custom brake lines to fit the legacy chassis. The SI drive is just a silly gadget so not worth the hassle of installing, all it does is change the throttle profile.