Running nitrous on the street is a pain in many ways.
You have to pay 45.00 to fill a 10 pound bottle. You only get 5-6 runs on a bottle. Then the last two runs basically suck compared to the first two.
Nitrous backfires are a nightmare too. Melting spark plugs with the N2O can happen also if you are even slightly lean.
You have to either have the bottle open all the time or have an electric bottle opener, because otherwise it is no use on the street.
somebody here is also confused about forced induction and gas milage. There is no boost unless you go wide open throttle so milage isnt affected in daily driving. I get 26 MPG with a KB at 11 PSI.
But maybe not everyone can afford the S/C over the nitrous, or like others have said, they may not want to give up the MPG for daily applications either.
But Nas, Boost, it needs to be researched and setup correctly for the car. I myself, I would rather have a supercharger or turbo than Nas. The bottle runs out, but the boost stays.
But again, as they say, "you can only go as fast as your pockets are deep."