Usenet Users - Max Throughput FTTC

[#1]

Hi Guys,
At my old address we had 23Mb ADSL2+, and I was able to download a 2.4MB/s, so basically fully maxing it out.
We've just moved house and got infinity at our new address, and sync speeds are 46.5Mbps, IP Profile 44.8Mbps and throughput on speed tests like Think Broadband and Ookla Speed test is about 42.5Mbps.
However, when using usenet, I can only seem to get about 40Mbps throughput, using 20 connections. If I move the connections down or up by a couple it doesn't make a difference, and if I move the connections up or down by 10, it actually goes slower.
Anyone got any tips for getting that extra 2Mbps?
I know it's being picky, but I'd like it

[#2]

You got flow control or anything else like that on?
I have maxed out my line using nntp (8MB down using sabnbzd) More connections can be detrimental on fibre try with 10 and work up slowly and see if it is better.
Saying that I just checked and I use 30 

[#3]

How can I check if flow control etc is turned on?
Out of interest, what's nntp?
I've always used 20, I dropped it to 10, then 15, and then raised to 25/30 and each one was slower than 20 connections.
I'm using Sabnzbd too.

[#4]

Check the settings for flow control in the router, qos settings.
Nntp is usenet protocol.
Otherwise looks like that is the limit, does your provider limit it?

[#5]

No, provider doesn't limit it.
Can't find anything to do with bandwidth control/QoS that's set in my router (I'm using a TP-Link WDR3600).
Seems like that's the quickest I'm going to get!