£200 from them - you could DIY for about £20!!!!
I know that this isnt strictly relevent but on safety grounds alone a single cable is just stupid!
The downsides of their mods are -
£200
you only end up with single cable operation - not very safe
their mod is completely overpriced and over engineered
I have a quick-action throttle that I fitted on my bike - £100 from Demon Tweaks - 1.5 hrs to fit from start to finish - works a treat.
But it doesnt help your idle issues - although I still dont know what you mean.
Khushy