The instructions advise removing the upper plenum bolts and loosening the bolts holding one set of runners to the base. That looked like a hassle, so we gambled that the upper plenum would come off without messing with the runners. We were right. The BBK regulator replaces the factory regulator housing but retains the stock diaphragm. Fortunately, the kit includes the tamper-proof Torx bit needed to make the swap. The bolt in the center of the new housing will provide adjustment.