I bought these about 2 years ago for the grey Calibra which died over a year ago.
I was told they were from a Mk1 Astra GTE. I suppose they could be from a Mk2 or even a Manta?

The seats have been stored in the shed since I bought them. They have been indoors for a few weeks to freshen up, but they still smell a bit musty.
They are designed for different bases. In order to fit the Calibra ones, I have used L shape steel section. Calibra seats are designed to have the bases fit inside so this has raised their height

I have cleaned them up & they were looking ok indoors but now they are fitted in the car, they look grubby.
They give much more support than the OEM Calibra seats. Why did GM not fit this style of seat to the Calibra in the first place? From my first few drives, they feel much more comfortable than the Calibra seats. I really need a long trip to judge this properly though
I like the more angular design but this may not be to everyone's taste.
They don't trap the belt receptor when the seat belt is flipped forwards. I find this really annoying with the Cali seats.
There are drawbacks though:
They don't have seat heaters.
They will be harder to keep clean than leather.
The steel section on the outside of the seat means that they sit around 1" or more higher. In the confines of a car, this is an enormous difference. The top picture gives a better impression as to how high they sit.
I can live with the top 2 issues (until winter at least), but I'm really not sure about the extra height. This has changed the feel of the car completely. I'll give them a few weeks but the extra height may tempt me to swap them back out again.