once again i will say this they crown of the pistion and the head look like that becouse metal was being smashed up there at 8,000 rpms the detonation would have been more in the center of the pistion if it was lean or a air leak it would have left a nasty little hole in the top of the pistions most likly what happend in this case was eather you have shitty luck and got a faulty pistions or the bore was bad crooked or lose somthing along the lines of that