There are two different types of FTTC cabinet that a customer could be connected to.
Huawei and ECI manufacture them. It turns out that the Huawei cabinets are the superior ones as they support features that the ECI ones do not.
G.INP and dBx are two such features, that, should you in fact be connected to such a cabinet, will get enabled in a few days time, further increasing your sync rate.
Now, I bet the next question is going to be - how do I tell which type of cabinet I am connected to?
Few ways -
Easiest would be to look up your address on the BT ADSL Checker by using a postcode check (telephone line would work too, but if you do not have a BT line then the telephone line check fails, as is my case on my Sky FTTC line as they have their own equipment in the exchange)
http://www.dslchecker.bt.com/adsl/adslchecker.welcome# - Click on "Address checker" on the bottom.
House number and postcode suffice.
When the result comes back: -
Address <redacted> <redacted> on Exchange ABERKENFIG is served by Cabinet XX
Cabinet XX is the key piece for me. We can then go look this up on the "CodeLook" site
https://www.telecom-tariffs.co.uk/codelook.htmLocality or Post Code to Lookup: I put in "ABERKENFIG" as that's where my exchange is, then click "lookup locality"
You can then click "All Exchanges"
Then you should see "Locality: <wherever you live>All Postcodes, All <xx> Fibre Cabinets <--- click this
You should then see a map with all cabinets represented, and a list below. You can find your cabinet, then identify what type it is from there.