I have a D17A2 engine and was thinking about getting a crower stage 1 cam. If I got one installed is a Tune required afterwords or would my ecu self-adjust?

 

Tune it. /story

A cam in a D series with nothing else is not going to feel much different, especially without a tune. Ask me how I know.

 

My ride does have a Injen short ram intake with headers and full exhaust system and its been ported out to get air flow flowing more smoothly so that being said, would their be a difference in power now and if so a lot or not much? Thanks

 

Not a big difference as I already said. The only way to get a respectable amount of power from a D series is to boost. Unfortunately, the D17 motor in the 01-05 is the worst for performance modifications IMO. Swap to K series and you will be MUCH happier (if you have the money of course.)