My understanding (from 'A Helicopter is Born' on Discovery) was that the Exec doesn't have an overhaul life as such; once it gets to 2500 hours, you don't return it to the factory or agent; you chuck it in a skip and buy a new one.
A test I read mentioned that on the example flown there was no low-rpm horn fitted. Reckon that if it's a good idea on the Robbo (and the JR, and (insert list here)) then it would be a good idea on the Exec.