/6 turbo or nitrous?

turbo is way easier on the motor!

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.