Well, have you ever found yourself in deeper water than you anticipated? I have. A couple of times in my almost 30 years of driving I've actually had water touching the underbody of my vehicle while crossing. It turned out to be a little deeper than I thought.
Standing water masks those dips and grades in the road.
This is how I look at it:
1. If I am in an area/road I am unfamiliar with and I cannot see the road, or at be able to maneuver around the water, without going off of the road, I dont go thru it. If I am in an area I am familiar with then I will be more inclined to drive thru water as I know said dips and grades.
2. Typically most places, especially cities, have good drainage and it takes a hell of a lot of rain in a short period of time to make something flood to the point of possible damage for cars. At that point Im on high alert, see number one if you are in an unfamiliar place.
I just so happen to live around Tampa FL which I swear quite possibly has the worst f*@%$ing drainage known to man! Just last week it rained so hard in about 30 minutes there was standing water everywhere. I happen to get caught in it, I was driving my POS 99 Honda accord. I knew the area well enough to know the any hard rain for more than 15 minutes causes huge problems and puts me on alert when driving.
Granted I dont give a rats if the car hydrolocked, I still would like to keep it, so I didnt venture down any roads that had standing water, unless I could see the road through it. Let me assure you, there were plenty of morons out that were probably less than an inch away from sucking up water cause they were in too much of a hurry they didnt want to turn around and find another way around said water.
I have spent some time in AZ during monsoon season as well and for anyone that has been thru that, knows what it is like to have a damn river flow thru a road. You dont have to worry just about hydrolocking your engine but your car being swept away completely.
I pay a great deal of attention to the roads. I know where the curves are, whats on the other side, how sharp it is, where there are dips that could cause undercarriage damages if I take it too fast. I drove an M3 once, and while not as low as a vette I was very much aware of the roads so I could comfortably push the limits without fear of damage or worse. If I didnt know the area, I would drive much more reserved until I became familiar with it.
Regardless of having the stock OEM intake or not, you can still hydrolock albeit harder to do. But typically only cause the point of where the air is first entering the OEM intake track is much much higher than an aftermarket CAI. IF an OEM intake were to injest air at a lower point, similar to a CAI then you would suffer the same problems. This usually only applies to cars though, for the NNBS I havent seen many aftermarket solutions that are pulling air from some ridiculously low point.
Im not saying your buddies issue wasnt all just a ****** combination of events but to blame it on the CAI, I think, is incorrect. Was it part of the problem sure, but it was in no way the entire problem. In my 20 years of driving on public roads and working on a farm since I was tall enough for my feet to hit the pedals, I have never come close to damaging anything from water related events.
**Maybe I am just being overly cautious**