I've run an APS Unichip piggyback ECU for the last 4 years in my 1989 RS legacy......and it's done me just fine. But it's basic as...fuel/air, ignition, timing. Some unichips have more functions than others.......some even have antilag. Here's he APS one
http://www.airpowersystems.com/unichip/unichip_more.htm
Here's the North American equivalent
http://www.unichip.us/21-what-is-the-unichip
I'm running V3 yellows, Walbro 500, an 18g TD05, and 3" exhaust. The unichip nets me around 40kw extra (over factory) at the wheels (around 190 atw all up) on a completely factory 21 year old longblock.............all day everyday......track days included........and not once has the Unichip missed a beat or dropped a tune
Duno what unichips retail for now but I've heard they can be picked up for 2-3 hundy.
If you don't wana go down the stand alone engine management road.........piggybacks are an option