Tweaking Sky Max connections ?

OK, my line is still only running relatively slowly, and I *think* i'm
just on rate adaptive DSL(? adsl max) rather than ADSL2 - i'm wondering
if anyone knows what you can do to try to force the issue...

This site appears useful, in that it can alter some settings in the
provided router:

http://dg834gt.mognuts.com/NetgearRouterUtility.html

When I check my stats, I think they're relatively poor (but i'm no
expert, i'm about 2.8km line length from the exchange), in that it's
reporting this:

Mode: G.DMT
Channel: Interleave
Trellis: ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 9.4 13.0
Attn(dB): 50.0 31.5
Pwr(dBm): 17.6 10.3
Max(Kbps): 4192 1152
Rate (Kbps): 3776 768

When it first connected my attenuation was only about 7 dB (!) but I
also think I had a faulty filter, as when the phone rang it was dropping
out. The new filter is ~50dB.

The site above has an option to select which connection mode the router
should use - do you know if it's "safe" to try changing from G.DMT to
ADSL2, or is this something the ISP sets somehow ?
(or should it be ADSL2+ ?)

The line speed calculator over at adslguide suggests I might be able to
get another meg out of it, but if the connection mode setting isn't safe
to play with i'll leave it as is...

Any thoughts ?

TIA