I've done a bit of research and found out it's better to use a long lan cable rather than a 15 metre telephone extension lead. Would I notice any difference, I'll probably be looking for a 10-15 metre lan cable. Will it lower my attenuation and by how much if possible? Some ISP showed after and before results using an extension lead and a lan cable, the attenuation was cut in half from 42.5 to 22.5. Also what kind of prices can I expect from high streets?
My exchange is 300 metres away from me, my attenuation up/down is 25/15.2