For the maximum street/strip LS1/LS2/LS6 aluminum cylinder heads AFRÍs all new 225cc emission legal head E/O #D250-4 are hands down the best choice. Specifically designed for 1997 to present Gen-3 Chevy Corvettes, Camaros, and trucks. AFRÍs LS1 head offers unmatched flow performance and features 2.080 intake and 1.600 exhaust valves with AFRÍs iron ductile interlocking valve seats. The 225cc is ideal for normally aspirated 396C.I. to 427C.I. For a wild 346 ci the 225 is a good choice, however some low RPM loss of torque might occur. It is available with 62cc, 65cc, and 72cc combustion chambers. AFRÍs LS1 is a direct bolt on, no special parts required. Structural features like Air Flow ResearchÍs trademark 3/4î thick head deck, a must for blown and nitrous applications, reinforced rocker stud bosses and thick wall runners provide unparalled durability. An exclusive new modern combination chamber design with double quench pad area helps the LS1 generate huge low and mid lift airflow numbers. If you need a snake charmer for that pesky neighborhood ñCobra Mustangî look no further! Chevrolet LS1 Small Bore - 225cc CNC Street Ported Heads, Assembled - 65cc Combustion Chambers