I believe he's asking how much power will you get from just a remap with no other mods.
And I believe that the engine is the same as every other 2.0TFSI so the increase is not as much for a DTM as a standard 2.0TFSI. Should be looking at 250-260BHP though. As for who to go for, well some people stick to the big guns (Revo, Custom Code etc) and some just go for the little companies (more-bhp etc). You will pay a lot more for a Revo map than a more-bhp map. I personally haven't got a remap yet, but will be getting a more-bhp remap sometime in the near future. Have read good things about them, and for £200 its the cheapest around.