ive got a DT, but from the days when dinosaurs roamed the earth, so no power valve
However, i always thought that they were designed to be a boost to performance, and so should be maintained in good working order, not to be considered a hindrance, but ive been wrong before, ask our 125 peeps...ojaxo?
Notice youve had an Aprillia bored out, maybe the DT seems slow after that...Just a thought.