Fibre upgrade 38/20 to 76/20

[#1]

Hi,
I'm 2 months left into my contract and thinking of upgrading from my current package 38/20 to the extra speed 76/20.
I would like to see how much faster my line would get I've tried DSL checkers and the lot but can be unreliable.  If I go ahead with this product change A) Does my contract renew? B) If no massive improvement, can I go back to 38/20?
Another family member is coming back soon and seen that when all 3 of us are online, the browsing experience seems to slow down.
Thanks
NE

[#2]

Hi buddy
You wouldn't be able to go back to 38/20 the package isn't sold by PlusNet anymore you would get 38/2....
Try here http://dslchecker.bt.com
That should give you a good idea of the speeds your line can achieve.....

[#3]

Upgraded last night.
http://www.speedtest.net/my-result/i/1600676386

[#4]

If you're on Plusnet 38/19 ( aka 38/20 or 40/20 whatever term you prefer) then your router (modem) will be syncing exactly as it would on 76/20 (76/19 or 80/20), can you see the sync speed on your device?  Obviously the actual throughput will be less than sync but you'd likely see 90% plus of sync if all is well.

[Edit, was posting as the previous post appeared but will leave this as the info should still be correct]

[#5]

Feel like my line can handle up to 65mb as when I was with Plusnet a few years ago on the same line I was getting 65mb down and 16/17ish up.
Using a cat5e cable from master socket to hub and cat6e cable to desktop.
www.speedtest.net/my-result/5215243895

[#6]

When you was with plusNET and got 60mb+ i'm pretty sure the cabinet would have had new customers since then? possibly the reason to slower speeds 

[#7]

@NE, what's your sync speed?  What does 'Further Diagnostics' on the BT performance tester say about your IP profile?

[#8]

My sync speed is 59mb
Interestingly when we got the speeds of 60mb+ there was only 20 or so houses on the estate.  
Now there is about 200 if not more houses on the estate and presumably all of the same cabinet.
I blame BT OR for not putting a new cabinet in place to serve the estate and using a one that was serving already quite a few number of properties since for ages.
speeds I'm getting now
This is where the fibre cabinet is and is certainly not a street side cabinet for us  

NE

[#9]

Did a bit of fiddling on the master socket and took out the filtered socket and opt for a micro filter.
Just to save out on an engineer visit you have to have drastic speed cut  I know everyone has different wiring etc but this is not good.
Don't know why it says my ISP is BT 
NE