I was torn between the Z1 and the Stillen CAI. I went with the Z1 CAI simply because no cutting of any existing components on the Z was required for installation. Jayhovah left you a great link for the intake/exhaust threads on this forum. Spend some time researching and don't forget to use the 'search' option if you need something more specific. Here is a link to Z1. They really are an awesome company to deal with and are beyond super knowledgeable when it comes to our Z's.
https://www.z1motorsports.com