508380S / 508380S - Application Notes The equal length design of these STILLEN headers allows better and more efficient exhaust scavenging which contributes to the performance gains tested on the dyno, 11.5 hp at @ 6200 RPM and 18.5-lb.ft @ 3800 RPM at the wheels. With STILLEN's 18 years of experience in designing and manufacturing Nissan performance parts, you should have complete confidence that every STILLEN product is of the highest quality and has under gone extensive research and development before production. These hand crafted shorty headers do not require the removal of the catalytic convertors and are available in two versions; 100% Stainless Steel or Ceramic Coated Mild Steel both are Manufactured by STILLEN. This part # is the Ceramic Coated Mild Steel Headers. Installation should be done by a qualified mechanic with proper tools and a lift. This is not a backyard bolt on. For the Mild Steel Ceramic coated Headers see part # 508380M. These headers do not remove the cats, but are not 50 state legal, check your area's regulations.