It's been a while since I've been on ADSL max (which I presume you are on), so I don't really recall what realistic speeds are.
There's a speed calculator based on attenuation here:
http://www.kitz.co.uk/adsl/max_speed_calc.php
My impression however is that it is somewhat optimistic. But, you should definitely get faster speeds than the 1mb plus a bit you are getting now. I'd see what happens when you remove that 'accelerator'.
What is your sync speed btw?