Old latest better than newest

Driving feeling on VW 1302 Super Beetle has been far improved in every scenery after applying the insulators on frontal wheel house, even the engine noise from behind has been far reduced.
In a more quiet condition while driving with additional 3mm thickness rubber sheet application, I clearly discerned the high frequency noise caused by gears and joints functional operations, they are propagated from trans-axle shifting lever.

Now I know that the intention of shift lever boots is not invited only for decoration but also for noise insulator. I just remembered that some manual trans-axle equipped old car had rubber insulator with relatively big volume on the shift lever, the first generation of TOYOTA Mark2?
The more difficult to eliminate when the more higher the frequency should be.

This kind of researching, experimenting and developing on the NVH establishment are all for the factory designer's task, not for the outsider's like a layman, myself, because the accumulated huge volume datum could have the right to say something on earth.
Suppose if I continue to eliminate the inconveniences found by chance the task should go indefinitely, because I have no way to know the ideally balanced condition for the vehicle?

Changing the situations, if I'm one of a member of the developing some specific model, without arguments desperate efforts would be required especially when rolling it out, and after that the efforts for more improvements would be continued till the next newer model would be rolled out again as usual.
So the matured form of the model would be the latest one as the model.