Originally Posted by CZAMFlyer

Much like an innocent kitchen renovation, one starts with the simple task of replacing or redesigning one component, but soon realizes that it leads to the discovery that additional and progressively more complex features require overhaul as well.

One can't simply redesign an engine cowling without understanding that the underlying engine itself, its size, shape, external piping and certification will all need review. That is most certainly not a "relatively easy retrofit", nor would it be accomplished within a year.