When I was test driving my boat just before I bought it (18C w/350), the guy selling the boat stressed that you never switch modes (either from wet to dry or from dry to wet) at anything other than at idle. Even though this didn't sound right, I accepted it as fact. I definitely don't see anything wrong with switching from wet to dry at high RPM's but what about the other way. Does the tiny extra back pressure to blow the wet leg out cause any adverse wear to the valves?