I'm of little help except to say that Master Cylinders are super expensive compared to just swapping out the levers. I'm looking into this same thing for my S4RS right now. I've pretty much ruled out the CRG levers because the Brembo versions are plentiful, cheaper, and I actually like the look of them better (but that's just style so - pah!). You may have looked all over heck and gone like I have but I'm liking the idea of sourcing from Yoyodyne for their good reputation and pretty good pricing. I of course will check with MotoWheels first to see if they stock the same thing as they do a great job of serving the folks on this list and I like to support our sponsors.