Had a few minutes here at work and found the following. You will find that the inspections regulation deal with leaking systems, if I recall. This is long, but its the Virginia Code Sections.
§ 46. 2-1047. Muffler cutout, etc. , illegal.
It shall be unlawful to sell or offer for sale any (i) muffler without interior baffle plates or other effective muffling device or (ii) gutted muffler, muffler cutout, or straight exhaust. It shall be unlawful for any person to operate on the highways in the Commonwealth a motor vehicle, moped, or motorized skateboard or scooter equipped with a gutted muffler, muffler cutout, or straight exhaust.
§ 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.
§ 46. 2-1048. Pollution control systems or devices.
No motor vehicle registered in the Commonwealth and manufactured for the model year 1973 or for subsequent model years shall be operated on the highways in the Commonwealth unless it is equipped with an air pollution control system, device, or combination of such systems or devices installed in accordance with federal laws and regulations.
It shall be unlawful for any person to operate a motor vehicle, as herein described, on the highways in the Commonwealth with its pollution control system or device removed or otherwise rendered inoperable.
It shall be unlawful for any person to operate on the highways in the Commonwealth a motor vehicle, as described in this section, equipped with any emission control system or device unless it is of a type installed as standard factory equipment, or comparable to that designed for use upon the particular vehicle as standard factory equipment.
No motor vehicle, as described in this section, shall be issued a safety inspection approval sticker unless it is equipped as provided under the foregoing provisions of this section or if it violates this section.
The provisions of this section shall not prohibit or prevent shop adjustments or replacements of equipment for maintenance or repair or the conversion of engines to low polluting fuels, such as, but not limited to, natural gas or propane, so long as such action does not degrade the antipollution capabilities of the vehicle power system.