Excerpted from Jeremy's blog.1aauto.com

Now this is where it gets good. The vehicletest.state.ma website basically says that Massachusetts follows California Air Resources Board (C.A.R.B) rules.

“Transmissions and transaxles changes alone are not legal. Transmissions and transaxles can only be changed along with their matching engine.” Ummm, What? I can’t replace my transmission without doing the engine at the same time!?

“Electronic ignitions or electronic point replacement units for vehicles not originally equipped with these items require an Executive Order to be legal for street use.” So I guess going from points to an electronic ignition is a bad idea now?

“Modifications that change a vehicle from fuel injection to carburetion or from carburetion to fuel injection also require an Executive Order to be legal.” …cringe.

“Headers for use on catalytic converter equipped vehicles require an Executive Order to be legal for street use.” Efficiency apparently does not equal cleaner emissions?

For all the info Jeremy found on Massachusetts safety/emissions tests: http://blog.1aauto.com/2011/03/31/massachusetts-vehicles-inspections/#more-4888