2 yrs, 3000kms and i'm yet top be pulled over (albiet only about 100kms of that has been between the hours of 6pm and 6am) - touch-wood
I think alot of it has to do with the hours you drive and where - if your driving it 3am in the morning in the middle of a night club district, your probarly going to get pulled up.
But i also beleive the cops would not distinguish between a 34gtr (lets be honest, usually drivin by older more mature drivers due to the price) and a normal skyline (which unfortunatly a small crowd has given a bad name on the roads). I dare say alot of cops wouldn't know the difference - they just see hoon car.
however, +1 on getting your number plate changed - you don't know what the last owner got up to in the car or done for a living and as indicated above, the plate could be flaged by the police.