Bills Pipes has long been synonymous with 2-strokes. Years later, even into the 4-stroke era, that hasnt changed. The legendary championship-winning performance and build quality pipes is unrivaled and is designed to give you every bit of horsepower and torque gains imaginable. 19-gauge AKDQ carbon steel construction Double nickel plated finish increases product durability and life Performance gains throughout the entire power band Hand welded and assembled for a precise fit Can be used with Bills Pipes silencer or stock silencer Hand-crafted in the USA