Hi slopoke and congrats for the new exhaust
(my being based in good ol' Europe means you'll have to bide with my "Olde Worlde English")
Anyway, the exhaust you just got is the typical European style exhaust, generally called "blow through"
It is made by one... 1.5 - 2" pipe, with lost of holes in it. It is wrapped with lots of tight glass fiber or rock wool, untli it can just be made to fit inside a larger pipe, which is the outer casing.
Imagine, thin pipe, wrapping around it, thick pipe.
What this means is that the exhaust gases blow the thin pipe, expand through the holes into the wrapping, so that's where all the high tones go. What is left is a low, mellow gurgle, which is what you hear.
Do NOT add baffles to the muffler, it's like adding shoestrings to a pair cowboy boots.
You did well to rejet the carb (how much, I'm looking to do the same, but I guess I'll have to PAY for my muffler)
By the way, have you fitted a tacho to the bike?
Regards,