I'm in the process of opening up the airbox and rejetting the carb.
Is there any way to mod the pipe for better flow?
I'd like to not exceed 96db's with the pipe.

Really? Nothing?

Never heard of anything before. You might be able to take out the baffle like we do on other bikes. Or grab a BBR pipe, and put in the Quietcore insert. Best advice I can give ya.  --L*64

Thank you for the reply. I'm rejetting for better starting and wondered about the pipe.

You already tried removing the spark arrester/baffle in the back of the muffler I take it?  I did that and think it helped a little combined with the jetting changes.  It didn't make it that much louder either.  I haven't looked yet but sometimes these play bike pipes will be restricted down to a smaller diameter than the rest of the pipe right up at the flange where they bolt to the cylinder.  The klx 110 is that way and we drill them out a little bigger.  Some feel if you go too far though you will hurt the low end power more than it will be worth to gain a little top end.