DMEs header is a 1 3/4″ to 1 7/8″ diameter step pipe 4 into 1. The big tube step header is designed for large engines and NOS motors and all out Grudge bikes (short-necked and d-raked). Fits flush with the bottom case. RCP will be stocking the 07-08 GSXR 1000 & Hayabusa sidewinder soon!!!