Hughes ...why not ask TC . He will know the answer as he is our resident 300 expert !!
Presumably you didnt realize that it has an electronic fuel cut off as well did you ?!!
As you still actually fly helicopters and fly the 300 ( so did i instructing but that was 1000 years ago ) it is interesting to hear your take on the possibility of reducing the engine rpm by either careful use of cut off or mixture . I can only guess that if it can be done someone will have done it !!
ps TC is also wrong about us flying the same machine unless you also run an old Agusta Mk2 !!!