And We have tried to "assist" with product improvement
Therein lies one of their biggest problems, all of these aircraft owners with better ideas than the engine designer and manufacturer (whom are not the same companies).
You've only got to talk to the manufacturer to realize that he knows far more about engines than 99% of the operators will ever know, but yet operators of these engines that have rebuilt their old motorbike or jet ski engine usually believe that they know more than the manufacturer. Many of the "improvements" suggested by operators of these engines are a joke and if other operators followed their advice they would end up in a box (and I am not referring to the engine being in a box!)