I have literally
just posted my cables off to Venhill (
www.venhill.co.uk) to get them to make me a set 120mm longer. About �41 for a pair of throttle cables according to their website.
I've heard nothing but good things about Venhill in the past, but will of course report back as and when I get my cables.
And of course once they've done mine you should hopefully be able to order a set without sending yours to them.