Hi bbb, you are one lucky kid for sure. When I was 16, I even had to save hard for my soccer boots!
As people on this board know, I own a R33 GTR. It's big and heavy but rather easy to drive and maneuvour around town. On the track, it's a different kind of animal altogether. The Beamer don't even come close though I would think that it is more comfortable than the 33 GTR. If you go for the Beamer, buy an M3 - stock 33 GTR is less powerful than the M3. But hell, the GTR is not merely a car, it is a driving experience in itself. Drive it, get to know it and it's capabilities, slam the pedal and you would never think of another car save probably of a Diablo! My advice, go for a test drive in both cars. Than decide.....I think I already know which one you would buy after the drive!