CAI with the K&N RX-4750 [that is the model number, right?]. That will yeild the best performance IMO. Somewhere there is the whole thread [I belive 5-6 pages] worth of info on the "rice pipe" <- search for that, w/o quotes. After that, a new catalytic converter [muffer too, if you want deep, throaty sound] will also help with fuel economy/performance. Some MSD coils/8mm wires/NGK TR55 plugs, will definatly help on the ignition end. Also, grab some seafoam motor cleaning stuff.. its like $5 at Napa, or Advanced auto.. that stuff is AMAZING! Also, while you are at it, flush the cooling system, and put in a 180F thermostat.. cheap insurance for longer engine life. Pretty much everything else is a little deeper into the modding.
'89 SSE - GX3 -190k, 155k on body - Back for another ride.