not chirp tires in a straight line. You can make the wheels spin if you brake boost and chirp the tires if you accelerate from a stop through a corner. The turbos on a stock Z are very quiet and barely noticeable. You can notice them if you drive next to a wall to help bounce back the sound. IMHO, it sounds like either you already have a really fast Z31 (and can't notice the acceleration) or something is wrong with the car you are looking at.