As you mention when using properly sized enclosures damping factor is not as noticeable because the speaker for lack of description has more room to breathe, i.e. the sound waves can disperse and not be directed directly back into the speaker causing the cone to potentially distort it shape and/or oscillate. In our case damping factor can help mitigate this issue particularly as the volume levels increase. As I mentioned before it is just one of many parameters to consider when dealing with our limited space. As noted my door speakers are not sub-woofers. They are the older discontinued models (bass/mid driver + tweeter) that are a direct fit (with small trimming of door panels) to our original factory units. I forgot the model but have the box somewhere and will post if I can find it. I used JL’s because the forum said they are one of the few that fit ( 3 screw mounting) and sounded reasonably well.