Turbo Manifold for Chevy Silverado/GMC Sierra (1986-1995) with 366/396/402/427/454 V8 EnginesPerformance Headers Chevy Silverado GMC Sierra Big Block V8 (1986 1995) Unleash your big block's legendary power with performance headers engineered for 366 396 402 427 454 V8 engines. Eliminate restrictive factory manifolds and unlock massive horsepower gains by letting each cylinder breathe freely. Why Headers Make a Difference Headers provide each cylinder with its own exhaust pipe, eliminating cylinder interference and backpressure that robs power