so if a car applied with klasse twins, i should only put OCW on top?
You can top it with a wax such as collinite 845, 476, 915, or OCW, or mother's step 3 - the important thing is that what you top it with doesn't have any cleaners that might strip the sealant.
The FX Synwax (paste and liquid) contains cleaners, so it might not be the best idea to put it on top of the Klasse twins.
+1 to this, though the cleaners in FX Synwax are milder than the Klasse AIO, it's either you use FX Synwax or Klasse Twins (AIO + HGSG), and top it with OCW as your LSP...