The FAA has approved hundreds of additional piston aircraft engines to burn the 100-octane unleaded avgas developed by General Aviation Modifications Inc. (GAMI).
GAMI’s unleaded avgas received its first STC in July 2021 for use in some Lycoming O-320, O-360, and IO-360 piston engines.
On Oct. 28, 2021, the FAA expanded the STC to an additional 611 engines.
Airframes approved for pairing with the engines will be identified separately on a list expected soon from the FAA, according to a report from the Aircraft Owners and Pilots Association.
A copy of the expanded Approved Model List is available on AOPA’s website.

I’m sure they spent a ginormous amount coming up with G100UL and deserve to get their investment back.
I think it’s a small price to pay so the EPA, et.al. Don’t shut light GA down!
YES, Bob
Ask to speak with Mr. Ben Dover.
Are we now going to have to purchase another STC from GAMI to burn their fuel in our aircraft which is already has an STC for Petersen or other auto fuel STC?
Per GAMI, they will be selling the STC for the G100UL soon, but have not set a price.
With 250,000+ piston aircraft, they look to make a substantial sum from it.