I've been running a 3100w Champion for over a year now. It runs the 15,000 btu AC on my camper plus a few other small things. I'm happy with it. Only issue I had was finding out it wouldnt run my AC at higher elevation (Flagstaff, AZ). Contacted Champion about it and they sent me a high elevation jet kit for the carb for free. takes about 5 minutes to change the jet if i need to, but now it works at elevation just fine. I have it mounted on the A frame of my camper. i built a shroud of sorts the keep the weather off of it and then lined the inside of the shroud with a dynamat type material. made a substantual difference on the noise coming in the camper.
