Helmholtz chambers are found on loads of off-the-shelf aftermarket exhausts nowadays (and some OEM ones) - they aren't complex/expensive to manufacture, making

Helmholtz chambers are found on loads of off-the-shelf aftermarket exhausts nowadays (and some OEM ones) - they aren't complex/expensive to manufacture, making them an easy option to tune the exhaust sound of a car. Super common in the muffler kits offered for things like civics, miatas etc to try and get a more exciting note out of a four cylinder.