Redbull661 had alot of info on the MS 661. Im still learning but IMO try modding a little at a time. You can always do more. Maybe pick up a used muffler to try something different. Thank you and good luck!
Use a slightly oversized drill bit and gently drill at the center of the spot weld until you can see the baffle is not connected on each hole. You may want to use a center punch to get a solid start for the bit. For the top spot welds you may need a small carbide burr or gently wiggle the baffle to break it free. Then clean it up. Hope this helps Mike. Thank's for watching!
@Mike Fries I don't know anything about whats done to your saw but If your just modding the muffler you could open up your side port to about the size of a dime. A little goes a long way. The stock cover should work well. You will most likely have to richen the high speed a 1/8 +/- so your not lean on the to end. Just a thought. Thanks Mike.
Hello mikefries2146, somehow I missed your comment . This 660 is ported with a Max-Flo, and I did open up the side port. This saw performs very well. I appreciate your comment, and thanks for watching
Hello Lex A, I do not claim to be an expert, but I've done 3 OEM and one AM saw this way. To clarify, ALL ARE PORTED with basically stock timing #'s and OEM muffler exhaust ports enlarged. 1 saw running a Bark Box & another w/piped cover, both equipped with Max-Flo filters. IMO, all saws pull 24"-32" W/aggressive chains & 8 pin drives , no problem. Don't know anything about your saw, tuning, or what you're cutting, but sorry it didn't work for you. I appreciate the comment, and thanks for watching.