If you really want to raise the exhaust then put some stacks up the back of the cab.
I have a snorkel and didn't raise the exhaust. Yes it is bad to get water in the exhaust but as long as the truck is still running it will not get any water in it. IF you stall out in water then you have a problem. The one time I did stall out in water it started back up fairly easily.
As for a snorkel. In reality are you really going to need a full blown snorkel. I mean think about it. If you are going to put your intake at the level of your roof you are going to have water in more places than you need it. Your interior soaked, heating ducts filled, electronics in the cab destroyed, water in tranny, diffs, transfer case, and your entire engine will be under water.
Are you truely doing the kind of wheeling where you need the snorkel that high. If you do make sure you waterproof your cab and put you vent extensions up to the roof line as well.
Now I thought about all that and decided I didn't need a full snorkel and a cowl snorkel would work fine. See my pics here http://www.ranger-forums.com/forum2/...3&page=7&pp=25
It has never failed me and I have gone through some deep stuff. The deepest ended up with me having 10+ inches of water in my cab. My air box was bone dry and the truck stayed running in about 38 inches of water.
If you are afraid of water being sucked in through the cowl it won't unless you put your hood under water. And if you are doing that then you need to water proof much more than your exhaust and intake.