RE: saito muffler thread sizes
Dave:
The FA-150 is 16 mm on the intake port only, the exhaust is still 14 mm.
If you have a 1/2-20 die, see if it will thread easily on the FA-125 pipe. If the pipe is 13 mm the 1/2 die should be 0.012" smaller than the pipe. and as I said, just 0.02 mm difference in pitch.
Bill.