What does water getting into the intake have anything to do with low gears? To be fair, the higher an engine would rev in a low gear, the more air it would want to suck and more water.
Water does not enter your exhaust, that was and is a myth.
An engine is an air pump, and a really good air pump. Water cannot enter from where air is exiting at high speed.
Water getting into the engine has more to do with the intake design than gears.