Over the past few weekends I've taken on several maintenance items on my wife's 02 WRX wagon. Only mods are Kartboy ss, bushing, and DIY grounding mod.
Thanks to advice and links from here I've done the following:
NEO RHD in tranny and rear diff. Wow, this stuff is awesome. There was a lot of info on diff gear oils, and I decided on NEO since it seemed to have almost all positive experiences. Rear diff was so easy, except I tried to do it without a pump at first. After 30 frustrating minutes trying to figure out a way to pour it in, I broke down, bought a pump, and finished the job in about 3 minutes, heh. Car shifts so smooth now. It was noticeably notchier after the SS, although I really liked the shorter throw. Now it's really sweet with slick action. I never really had problems with grinding, although reverse was sometimes hard to engage. So far so good.
Tranny was simple too, and I'm glad I got that gunk out of there. Magnetic plug had all this crap on it...
I've also replaced the fuel filter, replaced the air filter with a fresh OEM, flushed the radiator, replaced the headlight bulbs with Sylvania silverstar bulbs, and recent Mobil 1 5w 30 with OEM oil filter. Car is getting 10-20 more miles per tank. Maybe it's because I haven't driven the car much lately...
I have 4 NGK iridium plugs and a new PCV valve to install. Actually, I broke one of the plugs trying to close the gap, so now I need to reorder more. DOH!
The last thing I will tackle is the brakes. Not sure how much I will do, but I would like to improve braking perf. At least fresh fluid and new pads. If I'm ambitious, maybe an upgrade kit of some sort. Any recommendations for a street car, but with improved perf over stock?
Anyway, just wanted to share experience so far and thank people for input.