i have an os 46ax and i changed out the stock P-box muffler for one of the tower [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJB16&P=7]tuned mufflers[/link] i started the engine and it wasnt running right even with an adjustment of the high-speed needle. will changing the muffler require a new low-speed needle setting?

thanks

Yup, I would guess a little richer

I run the Tower Muffler on 2 OS46FXs, works great with about 600 rpm improvement but tried the TM on an AX and did not get much difference from the stock muffler with baffle removed. Either way you have to retune for this change of less pressure-richen low end and readjust high end -the AX seems to like the P-Box muffler. Also broke in and tuned an AX for a friend and came up with the same results.