Here is the Aluminum Exhaust Header the Traxxas Revo. Features: Aluminum construction Silver in color Fluted on tuned pipeline end for better silicone coupler connection Heatsink motor mounting flange Includes: One Exhaust Header Specs: Length: 59mm (2.32") Pipe diameters: Outside-13mm (.52") Inside -10mm (.40") Width between motor exhaust mount holes: 22mm (.866")