Thanks for the feed back, I haven't got far with this.... I've only modified cars in the past and the Tenéré is only my second bike.
As I'm not building it to race, I'm planning a twin piston calliper, new disc (standard size), braided hoses front and rear and standard pads. The trouble of fitting a larger disc for the very little extra performance isn't worth the effort, hence why I want to focus on the calliper. I don't have a disc protector so I can't increase the air flow.
I'll keep you posted,