Yamaha Outboards 425HP | XF425XSB2. The XTO Offshore is the result of years of collaboration with top boat designers, and has been built from the ground up to provide the ultimate in power and efficiency offshore. With impressive stats such as the highest compression ratio on the water, industry firsts such as an electric steering system, and engineering touches such as iridium spark plugs and quad thermostats, it’s purpose-built for extreme power, durability, control and reliability.