I have an '88 with the same engine. Oddly enough, with the number of these engines in use (Ford, Mazda, Kia all use it) there are very few specific mods available. I had the rear box of my exhaust replaced with a DynoMax Muffler & larger (they say don't go larger than 2.25") tail pipe. Most of the the exhaust restriction in my car was in this area - one look at the tailpipe & that becomes obvious.
Good luck finding an air intake set up.These guys:
http://www.itgairfilters.com might make one, but I assume it will be costly. PRM makes one, they are about $300.00 CDN. My setup is a Toyota AFM adaptor & a Hiper cone filter (This guy turned me on to this setup:
http://students.washington.edu/ruthless/index.htm) . This cost me about $70.00 CDN from Ebay.
Superchips does a chip for this engine. Their site says $295.00 US which is a little rich for my blood.
Corksport does a cam & header for the 1.6l sohc, they might be worth looking at....
Don't forget plugs, wires & distributor cap. I got some Bosch platinum plus 4 & some NGK high performance wires from Canadian Tire, the engine seemed much crisper after that switch.
Good Luck!