I installed caps on my dash and console over twenty years ago and could not be more pleased. They looked really good then, they look really good now. Not restoration perfect, but all but.
Any expert here on the Spider Forum would recognize the caps for what they are, but no one else has - not even when I have exhibited the car at Italian Car Day shows at Boston's MOT. (Where over the years it received two First Place, one Third Place and a People's Choice trophy.)
Installation was, as I remember, fairly quick and easy. For the dash this involved removing the dash-top vents, cleaning the surface, applying the provided silicon seal type cement, and pressing the units into place.
For the console pieces a bit more was required - especially the removal of the wood trim and, in my car's case, the separation of the `80s vintage Chapman hood lock/ignition disconnect unit (seen to the lower right of the steering wheel hub).
The one obvious flaw (which still annoys my wife) is that on the left hand side the cover sits a bit above the windscreen molding. Thus because the car had baked in the Florida sun warping the original dash.
Still, for a quick and inexpensive fix I was and am well pleased. And twenty+ years on it looks as good as the day it was installed.
-don