I have a 1998 Four Winds 5000 with a V-10. We live near Yellowstone park. The V-10 has no problems with the mountains. In the park, you are changing altitude from 6K to 10K feet. From Jackson Hole you cross the Continental Divide three times all in the 8K range. My V-10 and 23 foot MH had no problems and all the power it needed. It's the people on bicycles that will drive you crazy on narrow roads. Eleven-thousand pounds following a one-inch wide tire, and they don't like to move out of the way. In the mountains I get 9 mpg, on the flat I get 11 mpg, but I don't push it. Its the trip not the destination. Showing my confidence in the v-10, I just dropped $4k on the MH in preventive maintenance and upgrades.