As mentioned, I have an old Carbonex 20 Power which I bought years ago, but barely used as I stopped playing shortly after.
After almost 20 years I'm playing again and wondering what the maximum stringing tension would be on this racquet. It doesn't mention it on the cone.
I do have several new racquets which I use and generally string at 26 to 28 (prefer BG80 and 85).
Currently, the Cab20P is at 22 with BG 65 as I didn't want to stress the frame. It feels like I'm hitting the shuttle with a dead fish! I'd like to find a way to make this racquet feel somewhat closer to my newer racquets.
You can go up to 30lbs with BG65. If the racquet hasn't been used for many years, I suggest going to 25lbs first and then on smaller incremental step up according to your preference. This would let the frame get used to holding higher tensions in a stepwise progress.
Also factor in the stringing machine and experience of the stringer if you want to go higher than 25lbs.
Cab20power (should be blue colour) is a very strong racquet.