The 1st Generation Sierra propelled GMC into the 21st century as its best-selling vehicle. With optional LS power, the Sierra can be just as capable at the track as it is the worksite. Whether you're building an all-around street machine, off-roader, or track weapon, Holley has the parts you need to make your dream a reality.

Flowmaster offers a line of both Federal and California Catalytic Converters that are designed to fit and function on a large variety of vehicles. Only the highest quality materials are used to manufacture these catalytic converters. Stainless steel outer shell and heat shield construction provide long-term durability, while OEM-grade substrates carry noble metals meet or exceed emissions standards.