Homologation of variants costs much less than a new homologation. If it were not the case I wonder if the new Plus 8 would ever had been made.
Maybe, but different engines change the paradigm. The Plus 8 is mechanically identical to the Aero 8's, that's why the model was easy to make and sell. It's also the process that we used for SP1 which is a revised Roadster...
