Is it illegal to have blow-off valve in Massachusetts?

In Massachusetts, having a blow-off valve (BOV) is not illegal in itself, but it must comply with state emissions regulations. If the vehicle is equipped with a BOV, it should not cause excessive noise or emissions that would violate state laws. Additionally, modifications to the vehicle may need to be inspected to ensure they meet safety and emissions standards. Always check local laws and regulations for the most accurate information.