2004 has the new face, 2002-03 have the bugeyes.
mechanically, I think they're about the same, but there might be some minor differences I don't know about. I'm pretty sure there are slight differences in the suspension design - sway bar attachment & size, etc.
Pretty sure the 2004 got "better" struts.
The 2002-03 seats kick ass, the 04 seats suck. (you kinda sit "on" them, not "in" them like you would with the 02-03)
First thing he should do if it still has the original brake pads is put some Carbotech Bobcats on it. Depending on what else he wants to do with it (rallyx?

) he should check out
www.nasioc.com for info on modifications & any problems people are having.
when he decides what he wants to modify,
www.boxer4racing.com has pretty much anything he'll need.
Of course, the 2000-01 2.5RS is much more betterer...
