Are completely depressed the computer will set the rpm to a pre set rpm which we set off power band graph on the dyno sheet. It also will retard the timing and add gas to raise the boost to a preset boost level. So when you let out the clutch your at the perfect rpm and boost level. Ill bet Nissan never intended our Z's to do that. Lol
Watch a rally race video and listen to the popping noise between shifts when there downshifting coming into a corner, or watch ken block gymkhana videos and you will hear it too.