Specifications and features of HYBRIDFLOW headers for GM vehicles: Made of 304 stainless steel with full TIG welding. 1/7/8 long tube, 3-inch collector. Consistent lengths and an internal triangle for high airflow, increasing engine performance and horsepower. Compatible with GM Yukon and Sierra, and Chevrolet Tahoe and Silverado engines 4.8 - 5.3 - 6.0 - 6.2 from models 1999-2013.