Stay away from the little bolt-on thingies that advertise 5HP for less than $50-100. They are all snake oil and a waste of your money. Things like the airfoil in front of the TB, relocating the MAF sensor, throttle position sensor, or just a chip without other other mods. Larger throttle bodies don't really work unless you add displacement (bore engine), bigger cam and long tube headers.
You can gain some power with a good cat-back exhaust system like Corsa, B&B TriFlo's or Borla but expect to spend upwards of $800 plus installation if you don't have the tools or ability to do it yourself. I added a replacement K&N filter and cut a bigger hole in the stock cover, but I think the main benefit of the K&N is being able to clean and reuse it over and over again. Buy 3 replacement filters, and that's the cost of one K&N and a cleaning kit.
If you add something to get more air in, you have to have a way to get it out, so think of an air intake and exhaust as a package deal to get the best increase in power. However, IMHO, if the air intake says 20HP gain and the exhaust is a 10HP gain, you will just not see a 30HP gain from the motor. That represents a 10% gain over the factory 300HP and it would take much more than those two items to realize 30HP. Remember the 96 LT4 motor is rated at 330HP over the LT1 300HP and all of the difference is in internal engine components, not an air filter and exhaust system!
Your 92 should be capable of 160MPH speeds (my 92 vert is!) so that should be enough usable top-end unless you want to do open road racing or go to Bonneville! Swapping gears in the rear will be the best SOTP feeling of more horsepower. Something like a 3.73 gearset will provide a substantial increase in acceleration but you may lose about 25MPH on the top end. Gas mileage may only drop a couple MPG, but that would be well worth it.
Cars that go fast also have to stop. Make sure you budget enough money for good brakes. You can upgrade to the later J55 13" brake package found or ZR-1's or 95 and later cars. Performance pads like Performance Friction "Z" or Hawk HPS or HP+ pads are an inexpensive upgrade to your stock brakes. Don't forget a brake fluid flush with a DOT4 (DO NOT use DOT5!!) fluid and inspect the rotors for wear and calipers for any leaks. New brake hoses, too!