I purchased a 16’ boat with a 4stroke Mercury outboard. boat came from sea level and is now in Colorado at 5,000 ft. It has difficulty planing out. I put a 10 pitch prop but still has a hard time planing out. Once it gets past 41krpm it planes out and will run up to 55krpm. Can I change gears to high altitude? If so, where can I find them? Any other suggestions?