I have a 6600 and she it does OK with cheap thread in small doses, ie when thread painting on a landscape for eg. But for FMQ proper, I use Superior Threads, (Masterpiece, Bottom Line, King Tut), or Aurafil or Wonderfil. My thinking is you wouldn't buy a Ferrari and expect it to run on cheap fuel! I have seen CT threads but never used them - too fluffy and linty. Also you should have an 80/12 needle up to a 50 wt and a 90/14 for anything thicker. :-D