Starting in 2019 the California Highway Patrol will be enforcing some new roadway safety laws. One of them is the modified exhaust systems.
January first exhaust violations will no longer be correctable. A fine will become mandatory.
Therefore, you have to pay the fine and get the issue fixed. Before if you were cited you had time to get it corrected in order to avoid the fine.
Stay tuned as Bikernet will shine more light on this topic later in the week.