Is there a legal linit to how loud I could have my car horn?

Go for the gold and get 200 dB on your horn

>>17372383
27000. (a) A motor vehicle, when operated upon a highway, shall be equipped with a horn in good working order and capable of emitting sound audible under normal conditions from a distance of not less than 200 feet, but a horn shall not emit an unreasonably loud or harsh sound and a motor vehicle shall not be equipped with an aftermarket horn that emits a sound greater than 110 dB(A). An authorized emergency vehicle may be equipped with, and use in conjunction with the siren on that vehicle, an air horn that emits sounds that do not comply with the requirements of this section.