If your buying it as a NEW vehicle in any of the following states, CA, WA, CT, MA, ME, NJ, NY, OR, PA, RI, VT, then it's mandatory. Even if you buy the vehicle in an adjacent state, but it's first registration is going to be in any of the above states, you MUST have it. Like rear defrosters were in the 70's
What you get for that $200 is a different ECU ( part number and internal programming ) and a different Catalytic Converter. They will come into play in the future $$$ if/when they are ever replaced.
So seeing you are from Mass and buying NEW you probably will not have a choice.
98S, 2014 Impreza 5 dr Ltd (9 Subaru's since 1978, 7 were 5 sp) ILuvSubaru's