Currently it's a walbro 255 intank. The reg was hard mounted and I thought of rubber mounting but even with the reg removed and holding it in your hand the sound is the same. I was reading up else where that after market regs have a stainless needle and seat and pulsations from the fuel pump and injectors opening and closing can make this chatter. What's got me stuffed is the factory fuel damper is still installed but in standard form from the factory, the fuel damper is down stream after the reg on the return line. I thought you would want this installed either after the fuel filter/before the fuel rail, or after the fuel rail and before the fuel reg so the pulsation damper can actually absorb some of the pulsations from the fuel pump and injectors..