should i get a factory replacement? don't know the cost? or like an aftermarket lift pump, i do plan on adding more power in the future, but are they reliable/troublefree? or and i just skrewing myself even more.?

IIRC people were getting lbz CP3s because they were better. The aftermarket and dual pumps use the oem lbz ones. Someone will correct me if im worng

The only negative with installing the LBZ CP3 is you loose your core. GM will not allow a LB7 pump as core for an LBZ, but its unlikely most dealers will catch it.