Got a chance to get out and try my new macs clone pipe. It is very quiet--prop is louder than pipe. Seems to work good. I don't have the right prop for it yet (19x7 Skorepa) so I tested it with the APC18x6w. Pipe is 5.75oz and feels very substantial. Should work O.K. Tuned length should be for the low 8's and it was turning the 18x6w a little over 9. I
See 2 mb film clip:
http://home.comcast.net/~ccrsfield/OS16_Pipe.wmv