I previously had a Micron B Ballistix 2666 kit, max it would do was 3200 CL14 1.45v, and I think they can go up to 3600 CL16 now as the new 3600 kits use a mix of Micron B die that manage 3600, and E die that doesn't manage 4000.
Best thing to do is go as high as it lets you at CL14.