06-19 YAMAHA YZF-R6: Graves Progressive Throttle Tube Graves Motorsports Progressive Throttle Tube is designed to give your bike a progressive throttle pull and improved response over stock. This throttle tube is stronger, more durable and is a direct replacement for the OEM plastic throttle tube. Developed around the Graves Motorsports race programs. Constructed of 6061 aluminum. Requires slight modification of stock throttle housing.