Dieselr Aluminized 4" Cat & DPF Race Pipes | GM 2500/3500 6.6L DURAMAX LML 2015.5-2016The Dieselr Aluminized 4" Cat & DPF Race Pipes (2015. 52016) are engineered for maximum flow efficiency, durability, and precise fitment. Constructed from 4 inch heavy gauge aluminized steel, these pipes provide a smooth, unrestricted exhaust path that helps maintain cooler temperatures and consistent power under load. Each Dieselr system is mandrel bent for optimized airflow and precision welded for structural strength and longevity. The aluminized