[84LX89GT]

I believe if you go to:
http://www.esslingerengineering.com/
http://www.racerwalsh.com/

They have things like headers, camshafts, cylinder heads to name a few things. Unfortunately trying to get decent performance out of a 2.3L without going into the engine (performance rebuilding/stroking/porting) is like squeezing water out of a rock. You may get some more, but not a whole lot.

As far as i know a stock header from a late 90's 2.3L or 2.5L ranger will fit and provide some power. Other than that, if you want the car to get out of it's own way, investing in a turbo swap or a nitrous setup (can get for pretty cheap) would be the best for actual decent power gains. Also finding a way to eliminate the intake tract air resonator/muffler that necks down to 1 1/2" increases output a little bit. Also, getting an exhaust system from a SVO mustang lets you put on 5.0L size exhaust pipe/pipes. i believe the '86 SVO had a system that split to dual exhaust and had chrome pipes coming out the back.
Also i believe a couple years of late 90's rangers had 2.5L engines that are a direct swap, which i believe is something like a 13 cubic inch increase.
If you go to www.walkerexhaust.com you should be able to find something that works if you like, or you can get a system custom made if you like. Walker exhaust is the parent company of Dynomax. I have a sample picture included of their system.
Good luck on your seach.