Got my BG set-up running well, but it has whistled since putting it on. I tried lithium grease on the base gasket, then two base gaskets, still whistles. It does it at part throttle. It is loudest when backing off from full throttle. I sprayed starting fluid around the carb and intake at idle, no change in idle. I put a restrictor in the PCV line, no change. The two vacuum other ports are capped. It sounds sort of like blower or turbine whine, like a loud hiss. The carb is a 650 Marine Demon vac sec. I noticed the accelerator pump discharge hole with no screw in it, so I assume it's not coming from there? Do these carbs with down-leg boosters hiss? I tightened the baseplate screws before installing it. Do these leak around the throttle shafts at high rpm's? What gives?