The G911 is an Indy number afaik, and I have seen at least 4 different springs from them where the invoice listed them as "G911".

What I've been getting recently, listed as the G911, is about 150@1.900/350@1.300/CB@1.200.

Prior to that they were very similar to what would come on RPM heads, and I had a few sets of heads years ago where they were even softer than the RPM style.... Two different versions of those.
They were too soft to use on anything(IMO), so I ended up adding an inner to make them useable.

I just got some heads two days ago with the "G911" springs..... I'll have to see where they stack up.
It's always a mystery.