AFR’s, MONGOOSE, LS1 Cathedral Port cylinder heads are 100% 5-AXIS CNC ported and are CARB Certified EO #D-250-4 for vehicles model year 2004 or older. Made with A356 aluminum, all heads come with high quality components, such as titanium retainers and Pac Racing Springs. Available in runner volumes from 210cc, 215cc, 230cc and 245cc. Component upgrades and different machining options are available to customize your AFR heads for your specific build. Minimum bore sizing is 3.900” to accommodate intake valve clearance.