ive 1998 trans am auto, difference is some of these......
1.mine came with a standard cd player with a 10 speaker and built-in amp
2. leather seats with power controls
3. exterior sports package( dif. front clip, side rails,rear-end skirt,raised spoiler.
4. trans am have more horsepower than firebirds and formulas....some of the other guys can comment on the #'s.
not sure of dif. of exhaust systems, its all little subtle thingys. I know more about TA's and TA's w/ram than the base models(firebirds and formulas) think mostly its just amount of HP that been changed in the models.
Hope this helps
