Those cylindrical things on the back of Boost! What are they?! It's been bugging me forever! I'm guessing they're a kind of spoiler, but I ain't sure. From what I've seen in pictures, Ebony also has them.
NO2, or Nitrous Oxide 2, boost canisters. Often used to help boost the speed of a car that is racing against another or to help a car in performing a task, like jumping. Both Ebony and Boost have three each, probably to let others know of their high status and that they can go faster than any other tuner they are up against in a street-race.