I have always “felt” that speed brakes might increase the stall speed in a Mooney. However, never really read anything specific nor does the POH publish any stall speeds with the speed brakes deployed. So, thought I would take to the skies and do a “test” flight. I was a bit surprised and now believe I understand their effect better.
Stalls in a Mooney Ovation - effect of weight and speed brakes.