f150luke

Which would be safer and to my benefit, Nitrous or a custom tune? I heard ZEX nitrous kits are the safest way to add the extra ponies but im still not sure i was leaning more toward a dyno tune but some people say ZEX is better. Does anyone know or has had one of these done? I have an '02 F150 5.4L and was looking to get a lttle more than the factory 260hp.