2004 STi and 2006 WRX engine compatibility

[Jameseshepherd]

I have a possible problem with my 06 WRX engine
- excessive oil consumption
- possible head gasket failure

I have a 04 STi long block that I am current rebuilding (spun bearing) and am thinking of installing this engine in place of the 06, including stripping down the bolt on bits (alternator, air conditioning compressor, etc) and adding them to the STi engine.

Good idea?

Will I have any:
- ECU issues?
- parts compatibility issues?

Thanks

Jim

[dub81]

Having an 300 WHP motor in your 06 WRX is a step up from your current motor setup but IIRC dont the 06 ej255 have the AVCS setup already?? I know all the ej series motors are like lego's and and can put almost anything together so there wont be any problems. But with the ECu issue's, the only thing I can think of right now is the AVCS.