Hoping one of you Subaru experts will know the answer to this.

A friend has a larger-than-stock aftermarket fuel pump he needs to install and because the factory fuel pump controller won't handle the amp load of the larger pump, he needs to hard-wire the bump, bypassing the fuel pump controller. I did this too, when I installed my surge tank and put a giant pump in there so I can run E85 on a big turbo down the road.

My friend is telling me that two tuners have told him that if he hard wires the fuel pump, he'll need to install an aftermarket fuel pressure regulator and get a tune. That didn't sound right to me. I know the fuel pump controller simply restricts voltage to the pump during low-demand use, in order to lessen the amount of heat the pump is dumping into the fuel system and to extend the life of the pump, but the fuel pressure regulator works by simply returning as much fuel to the tank as needed to keep the fuel pressure at the factory level. The only reason I can think of as to why you'd need an aftermarket regulator is if for some reason the factory regulator can't return enough fuel to the tank to keep the pressure under control when using a large pump that gets 12v at all times. I've googled it and haven't really come up with anything authoritative on what point the factory regulator can't keep up. Clearly it keeps up just fine when the factory pump is at full voltage because the fuel pump controller does send it 12v at WOT, etc.

I've always run an aftermarket regulator in my 818 so I really don't know.

Anyone here know?

Thanks!