I'd say, look at the updates info in the FAQ. For the 3.2 cars, it seemed like 2000 was the earliest year w/ the most stuff done. Since '02, not a heckuva lot has been done, but that's the 1st year for the Celica headlamps. You can get krypton bulbs in <02 for not that much and there's even a DIY thing on here about it.
I prefer the 6 speed w/ the T top. A Zanardi would be cool, but having the roof off and the wind and sun is worth its weight in gold.