This is not the same old M20 header redone. This is our Tri-Y design that greatly improves exhaust scavenging. Our header has 1-3/4″ primary tubing that pairs opposing cylinders. In dyno testing our header was able to make 5-10WHP and almost 15ft-lbs Torque over other header types. We sell this as a complete system with 2-1/2″ from the header back. We tested 3″ exhaust with no gains other than weight. It also has two O2 sensor bungs to make adding a wide band easy. Now lets talk sound! Our header has a very unique low tone and beefy sound unlike any other system we have seen.