Reason asked about those mods is that I've chased similar to a rotted out battery
tray that allowed the battery to 'move' ever so slightly
K&N and thought might be their cold air setup and something came loose on that kit
If brake caliper associated, then that needs replacement. As that level of movement
to make that kind of noise says worn/busted/etc. The calipers are normally single
piston with a floating mounting system. There is an anvil that the caliper bangs
against to transfer forces to the steering knuckle and should NOT make any noise
Ditto the pads, they transfer to the caliper or to the cage
Without hearing it...tough to diagnose over the Internet. Ranges from loose stuff
already mentioned, to shocks, shock mounts/bushing, control arm bushings, steering
linkages and a huge etc