Yeah...this I know. However, my spring doesn't have the same "vibrance" it once had and base has dropped ~2 psi. I'm working on some changes to the stock boost control code and would like to ensure a proper starting point. I'd hate to compensate for a weak spring on my truck, only to have the bin overboost on a healthy truck. See my point? :tup:You can take it off the turbo, pull the rod , then place your finger over the tube where the vacuum line attaches. The rod should stay out. Proving the diaphram inside good or bad if it doesn't hold pressure.