Wow Horrible dyno setup with the exhaust facing a wall.😮 I gotta ask, do you have somewhat poor hearing? There's no way I would be standing there like that without some sort of ear plugs on. If it was vented properly or outside would be a different story. But I only get one set of ears. And once they're damaged, they're damaged! None the less boss setup!!
Give us a close look at the paint where the "protection" mats were sliding around... Detailing next I guess? -"What about the seals in there". Yeah, good question! Nice car and nice sound!
I removed the dampening cap with no heat and my wide mouth knipex alligator pliers..... didn't look like a good idea applying heat to a gas shock assembly imo...
At the risk of stating the obvious, I presume you checked corner weights at each wheel to ensure it was balanced? Or did you just go with your shock length measurements?