If it was indeed the weight of the muffler (insignificant in the big scheme of things) then you would be leaning left to balance it and it would pull left, not right.
Regarding weight, every one likes to make these grand claims about weight savings by replacing a factory muffler. They do it ad infinitem on the husky forums for the 630 as well.
So let's say you drop 8lbs for one, or 15lbs for two (mufflers, the husky has two), and 4lbs by ditching the stock battery for a Shorai...so about 20-25lbs or so, right? So you have a 450lb pig instead of a 475lb pig, and then pile gear and racks and all that crap on it. Same for the husky, so you have a 310 bike instead of 330. Wow. And you only spent about $60 per lb to do that. Most guys will say the money is better spent on a gym membership and/or rider training. A GSA or a S10 are still another 100-150lbs. I wonder if they use the same logic...
Oh, and then you don a 7lb adventure jacket and put a 3L hydration pack on your back. Sheesh!!