im getting my KW V2 coils installed on my e93 2morrow morning. i think the perfect drop to me is if you put your foot(with a sneaker on) the front bumper should hit your toe. thats the perfect ride height but of course you would go slow on speed bumps and try to dodge potholes. with your et 33 rear offset , you wont need to roll your fenders im pretty sure.
ill post some pics of my drop on my stock 189 wheels,(my work t1's with step lip should be done being made in july)
Bagged and Wrapped E93 335i