The water down the plug-hole sound is normal, I sound like that all the time...in fact it can be really loud sometimes! But when you say they sit heavy, what do you mean? I'm assuming you're not trying to drink too much at once are you, becuase that makes me feel a bit strange if I gulp/drink too much in one go, until it works its way through. I always have a milky coffe in the morning, but I can still get weird sensations, gurglings, rumbling, whinings etc for hours afterwards!