Detruire: For the record, there's a direct correlation between SNR and sync rates.
ie: With 12db, I sync at ~5800k/~10000k on two different lines. At 7db, ~6500k/11000k.
As long as the SNR is ~6db at a minimum, on a half-decent line a high SNR is a bad thing.
If you want to see the relationshio between Sync, SNR and Attenuation it approximates to:
Where FAST_MOD is a modifier for fastpath of about 1.25 when comming off an interleaved depth of 128
Working example at http://adsl.tin2tin.net/yourstats.php?speed_est_att=12