You should not have a problem adding a post-catalytic converter exhaust modification, i.e. replacing the muffler with a performance model; which by the way is really the only exhaust system modification you can do when using components which have not been tested and approved by the California Air Resources Board. The muffler is not considered an emissions component for emissions inspection purposes.
Note: Your Cayman's exhaust system configuration may not be tampered with. The addition or removal of an X pipe is not allowed. The oxygen sensor(s) pre and post CAT can not be moved from their original location. The muffler has to be a direct replacement of the stock part. If any modification is required to make the component fit, you're more than likely looking at a smog check visual failure. Prior to finalizing your purchase, get verification from the component's manufacturer that the product is legal for use in California.
posted by SmogTips Support 06-19-2017 02:40 PM