Of course it's not legal or at least moral. That wouldn't work on lots of cars as the vehicle speed has a lot to do with lots of other things and the car wouldn't run worth a damn.
Most cars are worth just servicing to make them pass and will run their best that way too. There is a problem in Massachusetts that cars from 1984 up must be tested and now the standards are so hard to meet with these cars if they were new it would be tough. They really want older cars off the road here. 96 and models the computer tells the inspection station a report on the history of the vehicle and if it has been cleared you won't pass even it nothing is wrong. Big brother government must know best????
T
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Tom Greenleaf - MetroWest, Boston