Hey, if you don't get a good response to your question here, you could try posting a query in the Non-Turbo Powerplant forum. Those guys know there stuff.

As for power, there isn't a whole lot you can do. Headers & exhaust for easy bolt ons. You could probably get new cams, but I don't know if any company makes upgraded 2.2L N/A cams...

 

No reputable companies make cams that I'm aware of. I've seen a couple of shady regrinds on Ebay, but that's about it.

 

Here are some of my favorite sites. You should be able to find some decent upgrades with these:

Teague's Auto (AKA Boxer4 Racing)
http://www.boxer4racing.com

SPO Motorsports
http://www.spomotorsports.com

You could also go down the turbo road. There are several companies making turbos for subarus and they should fit 2.2 as well as 2.5.

I'm currently installing a custom turbo kit on my friend's '95 legacy L (2.2L), and things are going quite smoothly. I'll probably start selling these kits as soon as we've tested them enough.

A good start would be a borla header and a custom exhaust from an exhaust shop. If you don't plan on turboing, go with a 2.25", otherwise, go with a 2.5". These mods alone will have a noticeable difference on the dynamics of the vehicle and may hold you off for a while.