My plexiglass top is indented 1/2mm (.02").

Plastic spikes w/o disks (no problem IMHO). I noticed that the spikes looked very similar to the plastic spikes on my Celestion subwoofer only a little larger. Probably from the same far east factory.

I did get a manual and my logo is mounted cleanly.

I'm still impressed with the deep, articulate bass from this modestly priced subwoofer.