Quick update, after disassembling the whole engine. Injectors flowed equally, spray pattern is good and none of them are leaking drops, so I can discard injectors as the reason of failure. Still pending to run the test on the AEM methanol system and see if its working the way it should.
There is some unusual wear on cylinder number 4, why would that be? why only on one cylinder? checking even further I noticed oil squirter for cyl #4 is broken wtf!!, could that be the reason, considering SR20DE don't even have them?
What is killing me is, I still don't know why I blew my head gasket at only 12psi