speed test from this site is saying 4.4meg to 6.7
6.7Mbps is pretty much the maximum speed you'll get from a "8meg" ADSLmax connection.
The maximum sync is 8128kbps, which will give a maximum IP profile of 7150kbps, which gives approximately 6.7-6.8Mbps as the maximum usable data throughput.
So, as someone has already posted, any speeds below 6.7Mbps will be due to ISP or exchange congestion (or both).
Which a line attenuation as low as 4db, go for an ADSL2+ LLU product (BE, Bulldog or Sky/Easynet) at the first opportunity - that way, you'll probably get much more than 8Mbps.
Ade
Giving UKFSN/Entanet a try
DL Sync 4288kbps
UL Sync 448