If you're going bracket racing, you really don't need either, unless you trying to run a specific class, such as 13.0 index. Generally, nitrous will make it easier to run the same number consistently.
why not go both! lol just kidding, prefer going turbo too because price starts adding up going with the bottle and a turbo your using that free energy from the exhaust to make that power and percentage wise you gain more power from a turbo then with a supercharger or nos IMO.
Absolutely, and you can run a 2.93 rear to keep RPM's to a minimum, drive it on the street, get 23 MPG and save your driveline from a nitrous shock as well as not needing a nitrous specific ignition (retard or advance mechanism). Although not technically "free", using the otherwise wasted exhaust power is head and shoulders more efficient than a blower, especially on a 6.