Side Pipes Legal in MA?

Doubt it, IIRC most states wont let you unless it came stock like that.

Modifying the exhaust in any way is illegal in all states to my knowledge.

Most shops in MA will not think twice about just putting the sniffers on the side rather than the rear.

Although one of the posters above was correct that "any modification to the exhaust system is illegal (aftermarket)" everyone knows that we can all disregard that. Virginia currently has a law in progress to allow modified engines, seeing as almost everyone I know has mods to theirs that aren't factory. (It's well past due anyways)

Anyways, I've talked to Borla since I ordered mine and to their knowledge there is no "side exhaust" law that prohibits where the exhaust is. I looked for any Virginia laws and there are none IMO. As long as it PASSES EMISSIONS you should be fine. Either that, or find a good friend who does your inspection/emissions and you'll be alright as well. Anyways, why should it be illegal? Think about the Roush Mustangs - they are a production car and they're not illegal? Hope this helps!