Boostline CNC Ported 821/823 Cylinder Heads - Pair

Top off your short block, or just upgrade your current setup with Boostline's CNC ported squareport LS3 heads! These are a factory GM head that have been CNC Ported. These heads start off as a factory casting from GM then enter Boostline's advanced manufacturing processes proven to generate the most efficient power in every application. We take great pride in our work and our attention to detail is unmatched in this industry. FED’s Boostline Heads Include: Seasoned pair of OEM GM heads Exclusive high performance porting programs via 5-Axis CNC – Intake/Exhaust/Chambers Pressure Tested for Leak Detection Precision Valve Job, which ensures near zero runout Meticulous Hand Blending and Deburr PCD Surfacing (Optimal For Modern MLS Head Gaskets) Final Wash and Assembly Extreme Attention to Detail and Quality Control at Every Stage 284cc Intake Ports 99cc Exhaust Ports 72cc Chambers Extreme Duty Stainless Valves 2.165/1.60 .660 Lift Dual Springs with Titanium Retainers These come assembled but do not include rocker arms or rocker stands. Flow Bench - 4.155" Bore No pipe on Exhaust Flowed on a Superflow 600