Surely 'blueprinting' is outside the rules too?
IN FACT - There is no reason to have an engine taken apart/re-built by anyone as you can't do anything to them according to the rules.
So it kind of begs the question, what are these tuners doing?
The rules allow you to fit an exhaust, air filter, PC3 or Dynojet kit and set the cam timing... nothing else.
How engines range from 58-68 is a bit confusing considering the lack of mods allowed.
Must be some good engines and some not so good engines I suppose.