easy way to check head gasket. start car cold with rad cap off if theres bubbles then headgasket. comp test and leakdown. good luck
ive seen 2 b16s that have took a dump when they werent tuned and hit only . .1 .2 bar. thats still boost and with stock managment it adds alot of timing and no extra fuel for the 2 or 3 pounds. if ur system is effecent then thats about 25-40 hp. enough to break a land with detonation even with a knock sensor is possible. ive been there trust me.... i just changed the pistons in my lude because of somthing simlar. well have fun