I have just installed a hardwired inline filter. It made a difference of 5Mb/s (11.8 to 16.8). I had tried the disconnect all your phones test prior to installing the filter but got very little improvement. I realise now that the house alarm is hardwired into the phone line prior to anything else and that possibly had a impact. The filter is now installed prior to the alarm. I notice most peoples speedtest.net posts are for the Auckland server. I am getting better speeds and shorter ping times using others such as Tauranga (Auckland server is closest).
Areas of Geek interest: Home Theatre, HTPC, Android Tablets & Phones, iProducts.