Michigan Motorsports 1.550" Stainless High Performance LS Exhaust Valves Fits 1997-2013 Cathedral Port LS Heads Fits Casting Numbers 243 799 706 862 317 241 853 806 Set of 8 Exhaust Valves Michigan Motorsports' stainless valves are a great upgrade for your factory LS cylinder heads. Made from high strength 21-4N Stainless Alloy, these one-piece forgings feature hard chrome plated stems and hardened tips for durability. Swirl polishing improves flow over the OEM GM valves and standard aftermarket replacements. These valves are designed to be a direct drop-in replacement for the factory 1.55" exhaust valves on the applications listed above and below. Fits Engine Codes: LS1 LS6 LS2 LQ4 LQ9 LS4 LY2 L20 LY5 LMG LMF LH6 LC9 LH8 LH9 LR4 LM7 L59 LM7 L33