Maybe I'm all wrong, but when I hooked up my kicker, I just came out of the other side of the filter. I was told that the ball on the queeze bulb would act as a one-way valve, as long as the direction arrow was pointed up. So I put the bulb near the kicker, where it would point up. No problems so far, 100 hours or so on the setup.

I suppose if there is a chance of a problem, the two valves would be the most secure way to go, but I'd hate to have to switch over every time I switch between the big engine and the kicker.