My 08 WRX's motor went out and I need to put in a new engine, or at the least a long block. I figured this might be a good opportunity to throw in a STI motor and get a few extra HP out of it. does anyone see any problems with this? I know I would have to change the ECU on it, but other then that would it be compatible? Also does the STI even get its extra HP from the Motor? I know the only real difference in the two is the heads.