Only their AK line is good, from my experiences, everything else needs quality control ^^
Plans thus far:
Madbull M110 spring
Systema area 1000 oiless bushings
Echo 1/Modify v3 spring guide w/bearings
Bravo gear set (heat treated steel-enhanced)
JBU 6.01mm tightbore barrel
and a Systema turbo motor (short)
I might eventually go full on systema for internals, dunno yet