If you really want to "tweak" your connection speed then you could try contacting either of these people
http://www.cableforum.co.uk/board/member.php?u=39
or
http://www.cableforum.co.uk/board/member.php?u=1586
and give them your I.P address and account info and I'm sure they could sort you out
Seriously though tinkering with anything in the config pages can cause problems and if you screw up your connection you will have to pay to have it sorted out. Get caught "tampering" with your config file to increase your service speed and you stand to lose your connection and quite a chunk of cash.