The whole maxdsl thing is up in the air at the minute. My line speed syncs at 7000kbps and has recently changed to on plusnet line speed page to reported 6500kbps, sysnc is always above 7000kbps on router, with downloads of 3.4mbs being the highest.
Plusnet have advised that BT are working on issues like this and are trying to sort them out. It transpires that everyhthing went wrong when things were submitted using the bt bulk upgrade tool. All customers upgraded using this tool can see line speed sync higher but only achive lower downloads due an error in thier upgrade tool code.