Nope, you don`t have to run a "nitrous" cam. However, it is perferred that the cam have more lift and duration on the exhaust side. Every nitrous cam I`ve seen has considerably more on the exhaust side as nitrous creates a very high amount of exhaust. But, you can run a single pattern cam just as well with nitrous, we did it many times. Some times when in a crutch when somebody already has a single pattern cam and they want to run nitrous they just add higher ratio rockers on the exhaust side.