Please forgive my ignorance. I'm interested in prep-ing a bunny for the track and want to know what my long term options might be. I haven't purchased the car yet and am putting together a pro and con list. I know I want an A1 Rabbit. I see that the early rabbits (1.6) are in ITC and the later (1.8) are in ITB. Is it legal to put a 1.8 in an early A1 and run in ITB? Will buying an earlier or later car lock me into a particular class based on the chassis year?

Thanks,
Allen