1998 4.6L with forged pistons stock rods. Vortec Sc. Boost crower cam. Fmu. Diablo AFm. Injectors. Did a 11psi pull and engine started tapping. One side also jumped timming and two pistons pictured damaged. What do you guys think caused this?

 

whats the rest of the build? what do the plugs look like cut the threads off and look at them close for black specks almost like pepper on them. Detonation. what was the rings gaped at? is the end of the piston ring land area is it like they were sandblasted? also a sign of detonation What size injectors? cant see the pistons all that well. As far as jumping time maybe thats why if failed also. did it pop a head gasket and get water in the cylinder then melt the pistons? is the head gasket bad?