depends on the tune and how aggressive your setup is. you have lower than stock compression and bigger injectors, but list no cams? and possibly a bad tune? id say if you have a stock or less c/r, and nothing more than stock on the top end, then you need stockish cam timing.

the pinging that you hear, from what i can tell, is the same noise you said you thought was spark knock from low octane. all spark knock is, is your air/fuel mixture combusting before the spark plug ignites, usually from overly hot weather or inadequately low octane. in your case, for the time being, set your cam timing back to 0, rotate the wheels a few times, very gently, to make sure you dont have any internal engine contact, and start it up to see what happens. worst case scenario it knocks more. just remember where it was in case you have to put it back.

GL