theres is one thing you have to do! i had the same problem like you not that long ago. for my y7 setup. i had bought egay headers and cat. one thing thats gonna suck for you is the donut gasket. its not gonna fit correctly to your cat so tighten as possibe. you are going to splice and sauder the secondary o2 sensor about little more then a feet BECAUSE the 2nd o2 sensor inserter is not mounted on the same place as a y8 would have it. i had bought a ex cat from a friend and tried this out already. due to our setup its mounted on the tranny next to the y7 cat while the y8 sensor is mounted near the rear of the tranny. yes my cat code did go away but now im getting a secondary o2 sensor high electrical ouput i dont know why. oh and also get a catback exhaust
