I used to take both, but now i only take Pulmozyme twice a day and it works great for me. The other one, not Mucomyst, but still acetyl-cysteine (it had a different name here) did almost nothing, it was mainly a waste of time.
I also take Albuterol or Levalbuterol and sometimes, ventolin(salbutamol), but only because I have them, not because i see any visible effect whatsoever.