Aeroflow Performance billetLS1 valley plate is perfect for those who want to clean up the look of their modern LS engine or create a custom touch. Designed to be low profile that will eliminate any fitment issues with factory and aftermarket intakes ad still take the factory gasket. Precision manufactured from billet aluminum with a modern, race inspired design and a cost -effective alternative to the factory GM pieces. This valley plate does not have the two provisions for knock sensors, which are usually not used in racing applications, as open headers, solid lifter cams and stiff suspensions can false trigger them. They can be used on factory and aftermarket GM LS1 style engine blocks. Will not fit Gen 4 Engine Blocks (LS3, LS7, or blocks with Active Fuel Management (AFM), DOD) use part number AF77-5016.