Skip the auto shop - Our mechanics make house calls

The Guide to Legal Car Modifications in Massachusetts

The Guide to Legal Car Modifications in Massachusetts ARENA Creative /

Whether you live Massachusetts or are moving to the area, you need to know about the vehicle modification laws to make sure your car or truck is street legal. From sounds to classic cars, the following information will make sure you know what to expect from the Massachusetts car modification laws.

Sounds and noise

Massachusetts regulations on sound are a bit vague in some areas. However, the following are what you need to know when modifying your vehicle.

Sound system

The sound emanating from your vehicle cannot cause the ambient sound levels at the nearest property line to increase by more than 10 decibels from normal sound levels. These regulations and subsequent enforcement defines noise as that which is of a duration and/or intensity that contributes to noise pollution in the air.


  • Mufflers are required on all vehicles and must prevent unusual or excessive noise and be in good working condition.

  • Muffler cutouts, bypasses or other modifications that are designed to amplify the sound are not permitted.

Tip: Also check with local county laws in Massachusetts to make sure you are following any municipal noise ordinances that may be more stringent than state-level laws.

Frame and suspension

Massachusetts regulates lift and suspension systems on vehicles.

  • Vehicles cannot be taller than 13 feet 6 inches.

  • Vehicles with a GVWR under 10,000 have a 2-inch suspension lift limit.

  • 4x4 vehicles must follow (wheelbase inches X wheel track inches) divided by 2200 to determine lift limit.


Massachusetts does not have engine swap or modification guidelines. However, all vehicles must pass emissions testing and general inspections.

Lighting and windows


  • Red and blue flashing or rotating lights are only permitted on emergency and police vehicles.

  • Fire department members can have red flashing or rotating lights on personal vehicles with permit that can only be used when responding to an emergency situation.

  • Failing to comply with the above regulations could result in a fine between $100 and $300.

  • Spotlights cannot shine more than two feet above the ground at 30 feet from the vehicle.

Window tinting

  • Non-reflective tint can be applied to the top six inches of the windshield.
  • Front side, back side and rear windows must permit 35% of light to pass through.
  • Side mirrors are required if back window is tinted.
  • Front side and back side window reflective tint cannot reflect more than 35%.

Antique/classic car modifications

Massachusetts allows vehicles that are older than 25 years old and used only for club activities, exhibitions, and parades to be plated as antique motor cars with the required Certificate and Affidavit of Vehicle Owner.

If you want to make sure your vehicle modifications follow Maryland law, YourMechanic can provide the mobile mechanics to help you install the new parts. You can also ask our mechanics what modifications may be best suited to your car using our free online Q&A system, Ask a Mechanic.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

How Long Does a Throttle Return Spring Last?
Not all vehicles on the road feature an electronic throttle control (ETC), which is also called drive-by-wire. For vehicles that don't offer this system, they have a throttle cable instead that...
How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
P0121 OBD-II Trouble Code: TPS "A" Circuit Range Performance Problem
P0121 code definition Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem What the P0121 code means P0121 is a generic OBD-II code which indicates that the Engine Control...

Related questions

Q: The car idles up and down. Replaced throttle body temperature sensor, mass airflow sensor, and oxygen sensor.

Hello. If you have taken all those steps and the idle is still not at the correct speed, then the next thing I would look at is the idle air control valve. The idle air control valve is the component...

Q: Does my 02 civic have shocks or struts or both?

Hey there, thanks for writing in about your 2002 Honda Civic. Your car has struts all the way around. There are pros and cons to lowering your vehicle. Make sure that you consider everything before moving forward with this modification!...

Q: I want to know what engines would fit my motor mounts properly

Hello. The biggest engine that this vehicle originally came equipped with was the 5.7L V-8. This is the 350 cubic inch version. I am not sure what modifications to your vehicle that would need to be done to make this...