I purchased a 2012 Rzr 170 in the last 2 months. We ride in PA and took it to Hatcield & McCoy (WV). Unlike you, we did get into mud and water conditions, so all may not be applicable.
I purchased new shocks and bigger wheels/tires, suppose to get here tomorrow.
From the dealer, I purchased soft roof, underbody skid plate, and front bumper.
Roof is great!
Bumper- well, it is much stronger than its frame mounts. My son tagged a tree while making a turn (~5 mph I would guess). The bumper had no marks on it, but the frame under the passenger headlight bent back 3 inches. The bumper was inside the plastic. This of coarse broke the plastic, but the headlight was ok. This impact was on far right of bar and bent all mounts, frame had to be heated with a torch and bent back in place.
Skid plate I would say is a must for us, but three of the mounting straps have already broken.
I plan on snorkeling everything up to the rear deck this week, there is mud inside the belt box vents.
I have to do some of the other mods described above as we have had the stalling issues in water puddles and cold start problems.
I hope that helps.