start with a low throttle and keep upping it!
I will say what I've always said: When you get a new isp, throttle your dl speed well below their radar, say for example, 10% of your maximum. Then, each week, add a few KBps to your maximum speed. This will keep you well below their radar. If everyone does this then the greedy bastards will be forced to upgrade their backbone accordingly or get rid of their customers.