What? Do you mean cut out the cat from the turbo section and then try to use the turbo downpipe or what?

You can use everything from the cat to the rear. Anything in front of that will not work because it is designed for the turbo set up and the 4g63 motor. Just unbolt the rear section of pipe from the cat on both cars and switch. Thats all you can do.

You can use the cat-back piping and muffler.

You cannot use cat or downpipe.