Yeah dude, like I said from the beginning a dyno session should be your top priority. If you intercooler isn't working 10psi is much higher than I would feel safe with, especially untuned!
Just because it pulls hard or seems fine, doesn't mean it isn't running lean or rich to the point of not being safe. I wouldn't get into boost at all without knowing exactly where I was at with my afr. Especially seeing that you bought the car as-is and didn't do the install yourself and are unfamiliar with its full history. I am saying this from personal experience with mine. These cars can take a beating, but if you go lean and detonate, thats gonna be a VERY bad day haha. Good luck with it man, sounds like a fun car for sure.