I've been using a stick to keep my trunk open, the torsion bars just weren't doing their job.
I have a pair of torsion bars from a car I parted out, so I decided to put the "newer" ones in.
First, removing the bars is a pain, so I gave up and started to put it back together when...
I discovered that I really hate to learn things the hard way.
Maybe you knew this, but I sure didn't.
There is a second "notch" for the torsion bar at the end with the 90 degree bend..
Took about two hours to do what could have been done in five minutes.
Now the trunk lid stands erect and proud.

But what do you do if they are in the second notch already? Mine are.

I've had the car since new and I cannot remember ever having moved the bars to the second notch. So (barring the first signs of dementia) they must have been in the second notch from the start. They still keep the lid open, but only just. A bunch of keys in the lock is enough to tip the balance. Annoying.

I should add that many years ago I installed a key-operated switch under the lid handle. The switch is no longer connected to anything, but I left it in place because it closes the hole I drilled for it. I am thinking of removing the switch and closing the hole with a rubber plug. That may help.

Simplesimon

Before discovering the second notch I toyed with the idea of sliding a metal sleeve over the torsion bar. It may have not done much, but might be worth a try.

Personal research!
or, "There's no substitute for experience!"
Congratulations!
The dern things are tougher than a 9-year-old squirrel!