just curious but did he swap out the springs locks and retainers?
I know they have 7degree locks and im pretty sure the springs are only good for .510 lift. I don't know if that would cause popping but it might be something else to look into that cold cause damage later

71 challenger 440 sixpack shaker *CLONE* (71challenger 440+6 shaker clone FAST/my HS grad present)
03 mustang Mach 1 (daily driver)

11.35 @ 121.5 4 SPEED on F60-15s w/ 6/32 tread