Tinggi

Back when I did my Z71 Chevrolet and other American brands it was simply pull the old pads and install new pads. If rotor was changed, so be it. Never a problem.
The LS400 demands attention to all parts of the brake system.
Cleanliness with cleaner to all components before assembly including rotor (do not put anything on face of new pads).
All shims and spring retainers in place.
Bed the pads.
Glazing can happen even on new pads/rotors! Then you have to break the glaze on the pads with an abrasive sanding pad, rotors can be tough to do but can be done.

Clean all and be sure all dynamic parts have a light cost of lube on them.

My 10 cents worth.