15% also works so well being it perfectly supports the 209 figure that Savagegeese got at the dyno. If the current car kept its 102.5 hp/ liter that means it makes 246 crank, minus 15% = 209. But yes, the losses could be lower and the actual crank could be lower too.
But only Subaru and Toyota know what is going on with the engine.
Part of me wonders if they are underrating the engine now because they know in the future, emissions will require they have to tune the engine more conservatively. So they don't want to list 240hp+ and then in 2-3 years have to list it as 228. They are listing it as 228 now, knowing that will be the actual number by the end of its lifespan. Have to wait and see if the car gets slower over time.
The 2022 Mustang GT just had this happen. It losses 10 hp.
https://www.cnet.com/roadshow/news/2...s-regulations/