No idea how much torque on the A2 VW, but it is even lighter than the mk III, right? 2280? So, it's torque is less than 120ft-lbs, real wheel on dynojet in IT trim?
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Realizing that my info is just one data point, and that not everyone here knows the VW stuff like Kirk and I, here are the salient differences between the A3 and A2 Golf:
A3 has 2 liter vs. A2 1.8 liter - much of this is longer stroke, thus my comment about expected torque gain
A3 has crossflow 8v head vs. A2 counterflow 8v head
A3 has an ever so slightly less desireable cam profile
A3 chassis is pretty close to a 11/10ths scale version of the A2
both cars can run rear drum or disk - and yes some think drums are better (I started this way, but changed to disks for ease of maintenance, and lower rotational inertia despite higher assembly weight).
A3 has 10.1" vented front disks vs A2 9.4" vented front disks
EDIT - A3 can run 14x6 or 15x6 wheels vs A2 13,14 or 15x6 options
A3 has a more advanced 'Motronic' engine management system, A2 can run Bosch CIS-E continuous flow system or VW Digifant electronic system (I run CIS-E, the A2 that ran at the front of the ARRC was Digi)
A3 is speced at 70# higher weight.

They are similar on the macro scale, but are different cars in the details, and have different strengths. I do think the A3 is the car to start with between the two if you want to go as fast as possible, but I am also a bit bull-headed and think I can build an A2 that can beat them - and hope to do that. Success or failure will both provide some fun times, but the former would be much sweeter.

You won't find me complaining often (hopefully at all, and if I come across that way it is not intended) about the competitiveness of my car of choice, as I beleive it is a 'prototypical' ITB car. I also appreciate that it has had a long run as one of the the front runners in ITB in general. A2 Golf owners are the last ones in the world that have a reason to complain about classing IMO.