Fuel Injector seal causing false knock?

[MagnumForceGB]

I have been chasing down why I'm getting 5 degrees of KR at 3000 RPM's and up to 10.5 degrees of KR at 7000 RPM's for the past few weeks. I'm even getting 4 degrees at 2000 RPM's. AFR can be 13:1 or 10:1, same thing. I've tried 3 different gas stations and I'm still getting it. I also noticed last year even with 104 octane I was still getting 4 degrees of knock at 4000+ RPM's. In 2 months after that the KR went to 10 and doesn't let up unless I'm having misfires on the cylinders and even then it just drops to 6 degrees.

Today I was researching more about the subject to fix my issue and I came across this service bulletin by Mazda for the Mazdaspeed 3/6. They have direct injected turbo'd engines. In the bulletin it says that the seals for the fuel injector can fail over time due to extreme heat and the constant pushing up of the combustion. My car has run extreme temperatures due to headers and constant runs down the track.

I'm curious as to what you guys think of this? I believe I can take my fuel injectors out but I would not know where to even get the seals from.

Attached are the pages from the bulletin that describes this.