Originally Posted by madscoob

sti will of had a z4 ecu and 440 injectors thats the only difference i think . the injectors will fit your fuel rails as will the ecu just plug n play engine differences are internals higher lift cams and i think larger valves . some expert will be along soon enough to tell all i expect ps both engines will of had td05 turbo the same , wiring loom the same unless ra with 5th injector . z4 ecu runs higher boost and slightly more ignition advance,