[KingLT1]

My brother runs JMS on stock pump a long with Cordes Auxiliary on his C7Z. It works fine on his car which is over 1k whp on E60. For anything 900 ish or lower just the Aux pump is likely fine on its own. Long as the pressure doesn't drop then you have enough fuel. My guess is those running JMS and Aux likely started with JMS and ended up needing more fuel as they increased power(as my Bro did), then added the Aux pump.