panels

So I’m going to be putting CCF (closed-cell foam) on my metal inner door panel and inter plastic door panel to prevent vibration noises from the door panel, as well as butyl roping some of the plastic components together, such as the clips. But is it worth it to do the same for other plastic...

So how do you guys go about making kick panel fit different drivers in case I wanted to change out in the future? I know I will. Concerned with overall diameter and mounting pattern. Enlighten me please! Thanks.