I modded my Zu DW speakers. Did some reading, talked to Sean, weighed pros/cons about what I wanted to do and ultimately decided I wanted everything I did to be reversible, bringing the entire speaker back to stock if I so desired.
What I did, added some high density Dynamat type anti resonant sheets to each panel on the tower excluding the top and bottom. I concentrated the material on the area of the panel that would be most susceptible to vibration. I understand that it’s easy to overdo this and in a sense take the life out of the speakers. It’s a balance between taking away unwanted resonance but keeping the desired coloration that the speaker is tuned/designed for.
The Zu have an interesting porting system which basically consists of 4 teardrop shaped slots on the bottom and a corresponding heavy density foam pyramid in the middle sort of isolating the area in the middle while keeping everything flowing to the slot. You can see what I’m talking about better in the picture.
The other thing I did is install a 10.5 in oak dowel in the area between the tweeter and the full range speaker as according to Sean at Zu that’s the area most susceptible to vibration and it’s a good easy and noticeable improvement.
Been working on it all day and I’m pretty exhausted, measuring thrice and cutting once and then trying to have everything aligned properly. Aesthetics and symmetry even on the inside. 
Looking forward to giving these a nice listen in the next couple of days. I want the brace to really cure before I pump up the jam.
