You can rev it to 9k but I honestly wouldnt. I would just get the ap2 ECU and plug it in, the 04-05's came that way from the factory so that's how I would keep it. Yes, if you get a different ECU you will have to have a dealership program your key to the ECU so it starts.

 

Revving a the F22 to 9K would be just as bad as revving the F20C to 10K...no way is that advisable and you would not gain much power anyway.