I would like your help to create a punch list of mods to complete before taking a new Cat out in the tough stuff. I will try to keep editing this first list to contain the punch list. I have both a 2007 H1 and 500 Auto. I'm sure this list can be applied to all models.

Water and Mud Riding Punch List (Edit 08/04/10)
Add Snorkels
Carb Vent Line Mod (2 or 3 loops of the hose before going to the airbox)
Silicone the 4 Wheel Drive Actuator.
Use dielectric grease on all electrical connectors.
Replace the fan fuse with a Circuit Breaker. (Bussmann BUS CB21215 Type II or BUS CB21115 Type I)
Replace the main fuse with a Circuit Breaker (Bussmann BUS CB21130 Type I)
Install fan cut off switch, to turn off fan when making water crossings.
The top of each differential has accordion bladder on them from factory, you can add additional bladder or vent it with a hose.
Install a one way check valve in the carb drain hose (HELP 47149 - UPC 37495 47149).
The battery is vented low but can be left as is.
The radiator can be vented into a Coolant Overflow Bottle (AC Part# 0413-086 with a Stopper (AC Part# 0413-087)
Add a aftermarket fuel filter, this will keep mud and other debris out of your engine. (Fram D-12)
Permanently mount cable or tow rope from receiver hitch to rear rack to use as an anchor point.
Line your inner fenders with silicone(or cooking spray) to prevent mud fron sticking.
Tighten EVERYTHING before you ride.
Check diff. fluid after every ride.