Kooks 04-06 GTO headers and header systems available at Xtreme Motorsports! 100% 304 Stainless available in 1 3/4" and 1 7/8" primary tubing. Headers can be purchased with front and rear O2 extensions harnesses as a set. Kooks custom high flow metallic cats or offroad pipes and X-Pipe assembly can also be purchased to make a complete Kooks matched system. Order your Kooks system today by selecting from the options below.