Predict ADSL+ performance...?

[#1]

ADSL2+ ordered - Is it possible to predict how ADSL2+ is likely to change my current speeds?
info from router currently is:
SNR 19
Loop Att 34
Up 448000
Down 4192000
thanks!

[#2]

I got this
[quote=BT Availability Checker]Our test also indicates that your line currently supports an estimated ADSL2+ broadband line speed of 6Mbps; typically the line speed would range between 4Mbps and 8Mbps.
When I put your phone number in the BT Availability Checker
Jojo