This is a past from another forum and the instructions I used Thanks to Gitsum.
It takes about 20 minutes to do, pretty straight forward. Turn the front wheels all the way to the left for access to the fender well. Remove two black hex/phillips screws on the bottom of the fender well right on the front wheel air dam (underneath the car), not the two silver ones. Starting at the front bottom inside of the fender well and working up, you want to remove the bottom two outboard grommets and a bottom inboard one. Use a flat bladed screw driver to pull the center cap out and unlock the grommets, they will slip out and be reusable.
You can now drop the fender well down far enough to reveal three 10mm bolts that secure the resonator. You will be able to pull the entire resonator off and there will be a small black pipe attached that came out of the airbox. Separate the tube from the resonator and trim the paper ring from the airbox end. Remove the lid from the airbox and pull the air filter, you will see the opening for the resonator tube. Firmly push the tube back in, making sure the resonator end points down towards the fender well. It fits pretty snugly, but I drilled a small pilot hole in the airbox collar and used a small sheet metal screw to make sure it didn't move.