Ultra Series forged pistons from JE are the industry?s strongest, most fully featured pistons available off the shelf. Offered for a wide range of import and sport compact applications from 2JZ to 4G63 and Audi to BMW, Ultra Series pistons feature JE?s proprietary Aligned Grain Flow forging technology providing next-level tensile strength ideal for the extreme cylinder pressures of power adder engine builds. Equipped with custom level features including thermal barrier crown coating, skirt coating, gas ports, and more, Ultra Series are the ideal pistons for your high-boost build. As with all JE Pistons products, Ultra Series pistons are made 100% in the USA. JE Ultra, BMW, N55B30, 3.307 in. Bore, 9.50:1, Inverted Dome/Dish, 6 Cyl. Piston Kit BMW 535i Base United States N55B30