Spec-D Tuning HH4-SIE99-DK GMC Sierra Yukon Chevy Silverado Suburban Tahoe Exhaust Manifold Header Fits 2001-2004 GMC YUKON MODELS ONLY. 2000-2004 GMC YUKON XL 1500 MODELS ONLY. 1999-2005 GMC SIERRA 1500 MODELS ONLY. 2002-2005 CHEVY AVALANCHE 1500 MODELS ONLY. 1999-2005 CHEVY SILVERADO 1500 MODELS ONLY. 2000-2004 CHEVY SUBURBAN 1500 MODELS ONLY. 2000-2004 CHEVY TAHOE MODELS ONLY. Made by T-201 ultra light weight polished stainless steel 4-1 mandrel bent piping type with C.N.C machined flanges made exhaust header Better air flow design. Improves exhaust velocity performance. Offers great flow and higher power gain Increases additional 10-15 horsepower approximately