Anthony,
While the Rabbit GTI is still a popular car in ITB (I used to race one myself), and there are a couple around the country that do ok, it is generally accepted (even among the VW crowd) that it is not the 'best' of the VW platforms for ITB. Primarily, because it is saddled w/ extra weight.
As was stated, they're great starter cars. They're a well known quantity, and there are plenty of parts available. They're also pretty inexpensive to run. The one thing you really need to watch are the front hubs. The axle nuts must be TIGHT. Even still, look at changing them out ever 4-5 weekends. The other thing you're going to want to consider is a fuel cell. Rabbits have a known issue w/ the fuel pickup in the tank. Mine, and several others that I know of, have 'hicup' problems in hard r/h turns if the car is less than half a tank of fuel.
Good luck!
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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608