Well guys, the story just keeps getting better! My buddy got his '09 XP 800 R back from the dealer on Thursday with two new pistons and one new cylinder. He is still running the dealer installed head mod. I have also since found out that he has a few other "secret mods" that he is not discussing.
We took off yesterday up here at Lake Vermillion in northern MN and he made it a mile and a half! The coolant bottle was completely empty and the engine was only running on one cylinder.
He was obviously done for the weekend, so after we got him back the rest of our group took off riding. There was another XP 800 in the group. By the end of the day that '08 XP 800 burned down and also needed a tow back.
The '08 XP 800 had the same head mod as the '09 plus they both had an aftermarket "Y" pipe and silencer. I am not sure if the mods were directly responsible for the break downs but is seems that the XP 800's are certainly running on the edge of reliability from the factory and any performance mod pushes them over that edge.
It looks like I may need to invest in a mod of my own if I keep riding with these Doo guys, a tow hitch!