I have an 06 Grand Prix GT and I would like to buy a tuned PCM for the car. I have read that for a 2006 model I would need to get a PCM from a 2004 model in order for this to work properly. Is this true or can I buy a tuned PCM from another 06 and install it? I don't have a tuner so I have no choice but to buy a pre tuned PCM. Thanks.