I've seen that hydro-lock happen in person on a 94 Firebird with a cold air setup that pulled low. Luckily he didn't break anything because he was idling, but spark plugs and sensors had to be removed to drain the water from the block.
Although I have many friends with that type of setup on their ImpalaSS that haven't had that problem, I went another route. If you do run a hose down low stay away from puddles[
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