My mobile test results are as follows: No vehicle electrical noise is heard with the resistor shorted or not. Not a problem.When the resistor is shorted, the residual hiss and logic noise heard when the receiver is squelched seems worse than my PRO-2067 and PRO-92s, which some people have reported as being annoying to them. With the resistor in the circuit, that noise is essentially gone. For me, that isn't an annoyance. Joe's mod for low audio is a winner if you don't mind that minor low level noise in a dead quiet room when the receiver is squelched and scanning.
I think I'll leave the resistor shorted and enjoy more audio power. Thanks, Joe!
John