I just learned from my regional SOA rep that Subaru of America has just received their updated ECM flash from SoJ for the USDM STi to combat the detonation problem.
Customers will need to leave their car with the dealer while their ECMs are sent to Subaru for reprogramming. There is an expected 4-6 day turnaround time, this is will obviously vary depending on a number of variables. Be very patient, it may take several weeks to get the process rolling on your car.
As soon as more flash units become available from Subaru, this will be a dealership-level flash service.
Let your dealer know IF you are experiencing detonation (NOT ALL CARS EXHIBIT IT!), and they will help you resolve the issue after testing and verification. If they aren't already up to speed on the issue, have them contact their regional rep for more information.
It may take some time for information to disseminate and to arrange scheduling through your dealer. PLEASE BE PATIENT through this process, this is not a recall so you will have to go through the full dealership testing, work order, and reporting process. There is an order in which this process must happen, please give your local dealerships the benefit of the doubt on this and allow the SOA reporting and resolution (flash) process to work as it should.