How deep are you going? I only shortened my air intake since it starts besides the radiator so it would start by the inner fender inside the engine bay. And I've never had a problem with water since then, but I plan to plumb it up to the firewall. Never had any probs with the diffs or gearbox and they can take alot of waterpressure before the doors start to leak.I do a lot of driving in water during the summer and most of it are streamy rivers.

1987 SWB Pajero 2.5 TDI on 31" rubber waiting for a hip replacement and bigger shoes