can someone tell me all the phases that the EJ25 went through all of the years and possibly what were the main diffrences of each? i read about the headgasket problems but were there any more? also the horsepower changes and which would you prefer overall?

The headgasket problem was with the DOHC EJ25 that came in the '98 2.5RS, there isn't a head gasket issue with the SOHC EJ25.
As for horsepower changes, there haven't been any that I have ever heard of.

The DOHC was Phase 1 and SOHC was Phase 2.

Both had the same peak hp and torque numbers but the SOHC had a slightly better power curve.

Between that and the head gasket thing, I'd rather have a SOHC Phase 2 if I was on a budget. On a monster build up I'd probably rather have a DOHC Phase 1 just for DOHC's ability to manage airflow better.