mustangsvt, The Skyline is a very formidable car, it takes a very logical approach to speed. Medium sized motor, two low mass turbos, 50/50 fr/rear weight balance and a two differential viscus coupled 4 wheel drive among other things. The Skyline is actualy banned from competing in many races (like the audi 4wd cars)because it's 4wd offers too much of an advantage(the ultimate in stability and controlability). The bad thing is it's price and it's also is not imported into the US, if you do find one it is a "grey market" car and most likely will be EXTREMELY expensive.
Before you buy a car I highly suggest that you at least go to one or two SCCA events. Or autocrosses and roadraces by other clubs, like the Porche car club, the BMW car club, etc. Get the real inside scoop on all these different cars from the owners themselves and see how they do out on the track. Do your homework first, ask owners about the things they like/dislike about their cars etc. And understand that going fast is quite expensive. You chew up tires, shocks, transmissions, brakes, engines, etc, when you go fast. If you can't afford to spend $2500 to get your transmision rebuilt every now and then or $1500 for a rear differential, $800 for new tires every 15000 miles etc, then I suggest don't go fast. Going fast is fun, but a very expensive hobby.