I don't know what tires yours has on it, but I have 235/45-17 Kumho SPTs on mine. They're pretty soft, with a treadwear of ~280 or so.
I can spin the tires in first gear for a bit; and traveling in 2nd, and turning, I can mat the gas and kick it sideways for 15 feet or so, but then it just squats and hooks up. (I don't do clutch dumps, since shock loading - and a bunch of torque - seems to be what kills Getrags. I've already killed one with a built 3.4.)
The engine is a 4.9 with Allante intake. Based upon the hardware, it should be making about 220 HP and about 300 lb.ft. I have not dynoed it, however, so that's pure speculation. The Getrag is supposed to have stock Fiero gearing in it. Based on speed vs RPM, I have to believe that supposition is correct.
I have the EP limited slip, but I'm not sure how much that really helps in a Fiero.