Corten Miller Performance are excellent at mapping omex, we did a custom dash for them in their demo car, its a civic turbo running omex which is now running over 500bhp.

Ben and Tom run the firm whom their late farther John started, great outfit with some very impressive projects on the go. Oh and the road that leads up to their workshop is like a race track

Incidently the interface between the omex software and the ms software are extremly similar so I see no reason why a mapper would struggle, I think that mappers are usually put off by ms due to the amount of poorly put together diy ecu's.