I've been running a 17/6 APC with pretty good results with the Abell muffler. I've tried 16/8, and 18/6W APC, but settled on the 17/6.
Would love to try the Mezjlic 18/6, but can't seem to find one. Nearest hobby shop to me is 70 miles, and they don't carry one that small. Don't want to order just one.