I don't know where best to post this snippet I picked up today from a colleague (user tamerocyte on here).

He had a remap done by E-maps (http://www.e-maps.co.uk/) on his MY05 BMW 330 Cd and when he took it in for a service, the franchised BMW dealer detected "some erroneous bytes" or something on his ECU code apparently during a routine upgrade and erased/flashed the remapped code back to stock! The remapper re-flashed it for him free of charge, but I had never heard of this happening before and was always (wrongly it seems) under the impression that main dealers don't touch ECU code and wouldn't detect a remap in any case. 

TTQS