Hyway dual port muffler

[Stihl123]

just wondered if any of you have fitted these? and if so what tuning screws you had to adjust?

also if you found much gain

 

HYWAY COMPATIBLE STIHL 066 064 MS640 MS650 MS660 DUAL PORT EXHAUST/MUFFLER NEW | eBay

 

thanks :thumbup:

[htb]

Did mine years ago on 660 (bought the front cover to convert to dual port) , to reduce the infamous flexible chain brake handle. Cured the problem and a worthwhile power increase only adjusted the H screw to get it to 4 stroke. Prob better to set up with a tacho, or be conservative and set up rich (check with plug chop)

[Stihl123]

ok thanks for that