My first question to you is, do you have to have your cars emissions checked in your area? If not, heres some tips, this is what ive done to my 2.3 in my 78 Mustang.
First off, buy a Header for it, im not sure of the exect part number of one that will fit the fox bodys, but i know they make em.
Second, do a full 2 in exhaust all the way back, no cat, and just a dynomax super turbo muffler, or a flowmaster, its sounds great at idle, a little bit high pitched when you goose it, but nothing like a ricer.
Second, you can buy a bigger throttle body for the engine, and bigger fuel injectors.
Thats about as far as i would go unless you really wanna try to make a race car out of it, then, youll be spending a lot of money for machine work to the head, but if you wanna go that far, heres what you can do if you wanna stay NA.
Put a larger stage 2 cam into it, itll lose some MPG, but still get quite a bit of power. Mill the head down 20 thousandths, no more, or youll have timing issues. Port and polish the ports on the head. Install larger intake and exhaust valves, and do a three angle valve job. Then youll have a beast of a 2.3, probably upper 100s of hp.
I have a 90 longblock in mine, and after the header, exhaust, and intake manifold (stock carb), it seems to have gained about 30 hp.
Heres some great websites,
www.racerwalsh.zoovy.com www.esslingerengineering.com www.cheaphp.com
Power for my '89 2.3L mustang 
