of course, like everyone says, get the t-link or some form of monitoring. Get a better fuel pump-most popular is the walbro 340, get better exhaust for performance, and get all the guages you can think of to see everything happening under that hood.
As for performance, depending on how fast you wanna go is the major issue. I want high 11's and I need a ton. If you want low 13's or high 12's, here are a few things you NEED: TA33 turbo or TA49 with compressor reclocked, 36lb injectors or better, ADJ FP Regulator, 3 inch DP, 3" exhaust or 2 1/2, but the 3 inch is always a better bang for the buck, a minimum 2800 stall converter, 87 computer, maf, mat and harness, ported irons and matched intake, headers from ATR or Postons, a chip burned from somebody you can get in touch with easily. (Jim Testa is real good-Turbojim on turbobuick.com), and a posi locking rear. You may also want to consider a cam like the lunati 206, or the more popular but never available speed pro 204/214 split cam. With those mods, you are looking at a 12 sec flat car. Get the right tires, and real good tuning, racegas, and you could hit even 11's with the boost turned up.
These cars are extremely tempormental when it comes to tuning. Tuning is key, and when your car is running near perfect, then hit it with all the mods...Once the mods are done, and you get that car tuned up right, that car will be running times that noone would believe it could for 20 years old and 3800 lbs. Good luck.
John