I thought for second that the A-100 van seats were the subject of your question.
Yes, they are nostalgic but also rather light (19 or so Lbs each) and comfy for what they are. Headrest a must for racing when a roll bar/cage is present. Detachable an option. I now know this since a little whipping on the neck can present a stiff neck and missing gears in an automatic. LOL.
DVW's seating is a great example of a light and oldie goodie. He's got some super covert tricks in those seats.

I've thought of messing with the frames way back, but I also thought, that is where my body mass is nestled and strapped into, so I chose not to play in that sand box, especially for a street car. Now mind you, I could get a pair of much lighter weight race seats if that's what you are referring too, but it defeats the purpose of visual deception. I'm just a sucker for those stockers of yore.

Man it can be said especially in the ounce count and gram programs, that it only gets super harder to shed compared to the humble beginning trimmings.
On that note, I know the project is knocking on the 2900 mark door very soon if not there already, but just have not had time to scale it again aside from running it lately.
When I reach that watershed number, I'll be sure to be on this board announcing it faster than a Government server.