Originally Posted by Red Bear

Is the rule of thumb "If it ain't OEM, it ain't legal"?

Originally Posted by Virginia Law

46.2-1049. Exhaust system in good working order.

No person shall drive and no owner of a vehicle shall permit or allow the operation of any such vehicle on a highway unless it is equipped with an exhaust system in good working order and in constant operation to prevent excessive or unusual levels of noise; provided however, that for motor vehicles, such exhaust system shall be of a type installed as standard factory equipment, or comparable to that designed for use on the particular vehicle as standard factory equipment. An exhaust system shall not be deemed to prevent excessive or unusual noise if it permits the escape of noise in excess of that permitted by the standard factory equipment exhaust system of private passenger motor vehicles or trucks of standard make.

The term "exhaust system," as used in this section, means all the parts of a vehicle through which the exhaust passes after leaving the engine block, including mufflers and other sound dissipative devices.

Chambered pipes are not an effective muffling device to prevent excessive or unusual noise, and any vehicle equipped with chambered pipes shall be deemed in violation of this section.