can go as low as you want. if you're going further than 60-70mm you'll probably need an engine lift as well. this is because the driveshafts have been designed to be a certain length horizontally, despite being on an angle. if you lower the car, you put stress on the shafts, which can lead to knocking in the corners as the splines jump, or snapping of driveshafts. a mate had a mk4 golf 110mm low. did nothing about it. he's a stupid bas**** and just kept fixing the problem thinking it was a standard problem with the car. he spent over £1200 on 9 sets of driveshafts!