So I read through the M5 service directions. The pumps on either side of the pan will pump the oil out of the heads when G forces are over .8. Unfortunately it appears they are plumed internally. The main oil pump is variable displacement(over engineered) vane pump. using the cooler lines would mean the the pump would have too allow a certain amount of bypass. At 113k on the clock it is possible. An accumulator would work for sure. It would only require a single tee connection and there is plenty of room behind the front reinforcement. The cost is about 5x higher than a pump though. Maybe I'll try a pump and if that doesn't work I can switch to an accumulator.