big wake marty

I live in UT and boat mainly at Lake Powell which is at 3500 feet elevation. When I take my boat to the mountain lakes near Salt Lake at an elevation of 7500 feet, I get no power. I can barely get a wakeboarder up to 24 miles an hour and no way I can pull tubers. I always empty the ballast tankls at elevation and still get nothing. It's kind of embarrasing to have the 24 foot enzo with the loud exhaust system and the boat tops out at 25. All the little bayliners are flying right by me. What is going on?