Add performance, durability, and longevity to your Duramax by upgrading with this complete valve spring and retainer kit from XDP. The XDP Performance Valve Spring & Retainer Kit features a conical design for better valve control over the standard straight spring. The conical design also allows for smaller and lighter spring retainers. Each spring undergoes a stress relief process and is computer load mapped to ensure quality and long term reliability. Each spring is matched within 1 lb of seat pressure to ensure consistency. Sold as a complete set with valve springs, retainers, and locks.