I had the same issue with the dB killer on my 2010 muffler (choking), but couldn't stand the noise with the insert removed. I ended up buying a FMF Q4 and am much happier with the tone, which isn't as sharp on the ears, and don't feel any performance loss. Very glad I went that way. The stock and Arrow race mufflers are too loud for trail work IMO.
(edit) - If anyone wants my dB killer or and/or stock muffler (2010 Arrow), PM me
Yep! With the insert removed it's noisier than the Arrow "race" pipe, and heavier so the aluminium Arrow's going back on in the morning.