Oh no man, you have higher than 9.0:1. You have a 9.7:1 CR engine. And a buttload of timing advance(my scangauge shows a peak advance of 50 degrees BTDC!!!). Head swaps do wonders for making stock internals take more boost. I am using EJ25 SOHC heads because they are some of the best flowing heads subaru made. Both EJ25 DOHC and SOHC heads flow much better than EJ22s and they will lower your compression to mid 8s. That will make things hold up to much more. Conservatively, I think you could run 10 psi without much issue on a EJ22 with EJ25 heads, many have run more. Keep in mind that this assumes proper tuning.
The reason I went with a WRX header setup is because the headers are better designed to get the exhaust velocity to the turbo, reducing lag time and the presence of heat shielding keeps heat in the exhaust that would otherwise radiate out with an aftermarket header. If you use either your stock single porter or the stock EJ25 header, these also do decently well. Maybe not quite as good as the wrx but they are thick piping and heat shielded.