Darton’s new Modular Integrated Deck sleeve kit for Rotax 1503 SeaDoo blocks allows you to go from a bore of 100 millimeters to a max bore of 104 millimeters handling any amount of boost. The kit is perfect for all applications whether it be full race, high boost, repair or just for the weekend warriors. The sleeves are individually replaceable or all of them can be replaced without re-machining the block. The sleeves are also phosphate-coated for added rust and corrosion resistance.