Yep I'm in the same boat. Have a 3mb
IBB line and while speed tests are showing excellent results my torrent speeds have gone way down even with private trackers*. I play a game called TMN and, while I'm not getting lag on the server, I am getting booted a lot lately because "connection closed" and also I have a lot of problems with pokerstars lately where I'm losing connection although Internet is still fine. i have tried all these with and without router, firewall, etc to no avail.
*In work I have Magnet Business Broadband which IS port restricted... restricted to 200kBs. Every torrent I download in work comes in at 198-202Kbs after about 2.3 seconds and stays at it til its done. Wish
IBB was the same!!