i thought about that also.. and i just hooked an NX kit up about a week or so ago in my friends car.. and i got thinking.. yeah a 50 shot feels a little more than an NOS 50 shot.. so there is a SIMPLE answer.. they are jetting more juice... power comes from two places fuel (actual fuel and air) and spark.... we know its not adding more spark.. so to make the shot stronger it MUST be adding more "fuel"

moral of the story... if a car can handle a 70 shot NX then maybe it can handle a 80 shot NOS.. but theres really not that big of a differance..