Kawasaki pumps up the volume. On the figurative side, the company has given its flagship Ultra even more power. The Jet Ski Ultra 310LX adds 10 horses to the previous model, but the minor jump isn’t about bragging rights. It’s the result of engineers fine-tuning the existing engine for increased durability and efficiency. New is a heat-resistant plastic intake manifold that boosts both low-range and midrange power, cast pistons with a groove pattern designed to improve oil retention, a freer-flowing fuel pump, one more oil jet per piston to keep the engine cooler, a slosh-reducing oil pan, an additional sound-reducing water box, and larger oil return holes in the crankcase. At the pump, the impeller sports a new three-blade design and longer nose, with the promise of increasing acceleration while reducing noise and rattles. Add this laundry list of tweaks to an already-powerful 1,498 cc engine boosted by a supercharger/intercooler combo, and you’ve got a great boat made better. Acceleration during testing proved brutally strong, with a newfound midrange snap en route to the peak speed we achieved of 67 mph.