2 New 1600 Dual Port Performance Cylinder Heads for VW Volkswagen cut to 94 bore with 40x35 Big Valves and Dual High Rev Springs for 1914cc pistons and cylinders. Don't be fooled by cylinder heads with stock 14mm 1/2 reach spark plug holes and stock combustion chambers. A 12mm 3/4 reach spark plug is far superior when dissipating heat. There is more surface area on a long reach spark plug to dissipate the heat. 12mm 3/4 spark plug also has much less chance of stripping the spark plug hole threads because the threads are 3/4 inch long instead of only 1/2 inch. 12mm spark plug holes are further away from…