ummmm, there isn't one?
There is a fixed wastgate on the Seneca's I flew for my IR. Hence to set t/o power you advance the throttles only about half travel to get the 40" for take off power, but then every 1000' have to keep pusing them forward to maintain climb thrust. If you exceed 40" by much, a flap opens to prevent you overboosting the engines, and you get a yellow overboost light on.
C.............ough