Massachusetts exhaust/emissions laws

Technically removing or modifying any working catalyst is illegal.

Realistically so long as you dont throw a P0420 catalyst below threshold CEL, you'll pass, unless they want to climb underneath and do a visual.

so from what you guys are saying in order to pass state inspection my exhaust has to be 100% stock? How do I see so many new cars with exhaust mods that have valid inspection stickers?

As long as you pass the OBD test and the muffler does not exceed threshold DB you pass. Removal of a cat, IF it is possible to visually verify can fail you. Use friendly shop!

No, it doesn't have to be stock. If you look into the regulations, i believe you can modify the exhaust, but you cannot increase the noise output of the vehicle. The chances of getting a ticket for a mild exhaust is almost nothing, obviously, but if you put catless pipes on, and a no muffler or very loud muffler setup on your car, then you increase the risk of getting pulled.

Now, granted, most states have similar laws (CT does, i know) but if you keep it reasonable, you should have no issue.

When you start messing with the emission system (egr, cats, etc) is where you can start to get in more than a fixitticket problem, and if you look at EPA's fines... the decision is up to you.

Keep it civil, and dont give anyone a reason to pull you over, and you should be fine.

here's the law

http://www.mass.gov/legis/laws/mgl/90-16.htm

I did not think that noise amendment passed in MA? It used to be it you could have it up to a certain db level. If that is now the case, it may not be legal to modify the exhaust at all? However it seems nune of us have had an issue passing.

There is a max DB level, and many cops carry DB meters. It is legal to add a new exhaust (after market) as long as it passes the DB test. As for gutting a cat, they got to get to it first.!

Put on a catless up pipe and a catted down pipe. As for exhaust, I like the stealth of quiet.

You can do a CBE no problem and pass in MA. I have a greddy SP2 on my wagon, stage 1 plus TDC tune and have passed. I have never been stopped or hasseled by the cops for noise from the exhaust either.

Going stage 2 without hi-flow cats would be a problem. Going stage 2 with hi-flow cats is better but there is no absolute guarantee that you will pass emissions, however many members here have.

looks like that amendment made it according to hakgwai:

"No person shall use a muffler cut-out or by-pass. No person shall operate a motor vehicle on any way which motor vehicle is equipped (1) with a muffler from which the baffle plates, screens or other original internal parts have been removed and not replaced; or (2) with an exhaust system which has been modified in a manner which will amplify or increase the noise emitted by the exhaust."

looks like that amendment made it according to hakgwai:

 

"No person shall use a muffler cut-out or by-pass. No person shall operate a motor vehicle on any way which motor vehicle is equipped (1) with a muffler from which the baffle plates, screens or other original internal parts have been removed and not replaced; or (2) with an exhaust system which has been modified in a manner which will amplify or increase the noise emitted by the exhaust."

This was directed at MCs. It does not preclude an after market mufler. Note the bold type.

I think there is plenty of room for argument there as well. However it is worded as such to include all motor vehicles. And i think part (2) would be more of an issue.

My point is, that it is easy to look at an MC exhaust system. It is VERY hard to see the cat system on a Subie. If you get stopped by a cop, it is unlikely (and actually illegal) for him to even pop the hood for a look IF the exhaust is not noisy.

It is easy to look at the DP to see if there is a cat. It is almost impossible to look at the UP with the engine cover on.

No person shall operate a motor vehicle on any way which motor vehicle is equipped (1) with a muffler from which the baffle plates, screens or other original internal parts have been removed and not replaced; or (2) with an exhaust system which has been modified in a manner which will amplify or increase the noise emitted by the exhaust.

Current emission testing for all 1996+ OBD-II vehicles in Massachusetts is limited to a simple OBD-II diagnostic scan, and a quick "visual". There is no guarantee that they wont at some point in the future also require a random tailpipe probe testing.