Mock up the helmholtz resonator just after the highest bend in the exhaust system. It goes right in front of the spare tire, and just after the rear end. You will want it to almost touch the spare tire, just make sure that you have a finger width between the helmholtz and spare tire. Make sure that the helmholtz points ‘up’ slightly because theoretically it could fill with water. When mock up is done, use the provided clamps to bolt it onto the tailpipe. Then mark around the entire base of the helmholtz with a sharpie. Remove helmholtz, then remove tailpipe out of vehicle. Use a 2″ hole
saw to drill a 2″ hole in the center of the mark. Re-install and adjust tailpipe, then install helmholtz and securely clamp down exactly as it was during mock up.
Check out this video at 10:15 for easy Helmholtz instructions.