Being an avid tuner of the Bronco 2, i have a few tricks i'm willing to share in the terms of performance and speed, BUT YOU HAVE TO READ THEM CAREFULLY AND SERIOUSLY!
if you're allowed headers (non-upright of course), then that'll definately give you some balls to stick to the walls. i got mine from AZraceplace.com.
being a '90, you have smaller valves and a less aggressive camshaft than an earlier model 2.9 (86-87).
a cheap trick would be to get an '87 engine that has been babied all its life, and use your computer with it. this is my little secret that's not a secret anymore: the earlier engines had bigger valves and slightly more bumpier camshaft, so with the newer ecu, it thinks it has smaller stuff than it actually does, resulting in a slight power up.
also, make sure you run a dual exhaust (if you're allowed). AND FOR CRYING OUT LOUD, DON'T PUT A 2 1/4 SETUP!!! go with at least a 3" single straight pipe, or dual in dual out 2 1/2 muffler with crossover. flowtech and magnaflow are great brands, not flowmaster.
the port and polish match is a sure-fire way to score some extra horses, though realistically it's only about a 6-10 hp difference, if done right. also, the factory throttle body is restrictive, and has a casting line right before the butterfly. THIS HAS TO BE SMOOTHED OUT. be careful though, as you don't want to make a gap under the butterfly. you only need to smooth out 1/16" on both sides of the butterfly, and make sure to get any casting lines elsewhere you see. DON'T GET SHAVINGS INTO THE INTAKE. take it off before you do this. and get that while you're there.
LAST BUT DEFINATELY NOT LEAST:
bypass the EGR. it's simple, the headers won't have the fitting for the egr, so just disconnect the pipe from the front-driver side of the throttle body and plug the hole. leave the sensor and diaphragm alone. also, bypass the PCV. this puts oily, dirty air right smack on top of the butterfly in the throttle body. just buy some hose that fits the existing valve, and an extra valve, some silicone, and run the hose from the throttle body right behind the air filter, with the spare valve in the middle of the hose. use a couple of inches to keep the old valve where it is, just point it out of the way.
IF YOU HAVE READ THIS CAREFULLY, SLOWLY, AND SERIOUSLY... you should end up making an extra 25-35 horses total. maybe more if you're good....
well, i've spilled the beans. GOOD LUCK AND PLEASANT VICTORIES!!!!