Change CAT? What nonsense. What operators? Not one that has a firm grip on their AoC. Again, AIP/Jepp is crystal clear on what determines performance category. Show me where it says you can change CAT from B to C.
Jepp Terminal AU-16
2.1.2 An aircraft must fit into and be operated in accordance with the requirement of only one category. An aircraft:
a. may not reduce category because of a reduced operating weight, but
b. must increase category when actual handling speeds are in excess of those for category (based on Vat) detailed in para 2.3