At the Yamaha test facility in Bridgeport, Alabama, I had the opportunity to test the XTO in a quad installation aboard a Grady-White Canyon 456, a triple installation on a Contender 39 Tournament ST, and a single on a Sportsman 267 Masters. If there is one word I’d use to describe the experience, it would be thrust. Yamaha claims the XTO produces 150 percent more thrust than its F350, one of the current standard-bearers in big-boat outboard propulsion. I noticed it right away on the Contender 39; while cruising at 3,500 rpm, I pushed down the throttles and felt the oomph as the triples rapidly accelerated the boat from the mid-30s to a mid-50 mph speed. With a crew of eight on board and a nearly full fuel load, I could push this boat close to 70 mph. In different conditions, Yamaha’s testers recorded a top speed of 72.7 mph at 6,000 rpm.