Mercury - Vented Splash Cover Pro XS V8 Series Polysoft II Marine Material 8M0228535. Overview. If you spend enough time on the water, you start to appreciate the gear that quietly has your back. That is how this Mercury Vented Splash Cover feels on a Pro XS engine-steady and dependable, almost like a shield you forget is there until you notice how clean your cowl still looks at the ramp. When I slide this cover over a 4.6L V8 250 horsepower Pro XS, I get the same sense of calm I feel when check