Well, for tuned exhausts I heartily recommend the pipe from Sick Bike Parts;
Sick Bike Parts
There's a few with pocket bike pipes, they cost less but require a bit more ingenuity lol They are just a touch louder than baffled/stock - but it's a nice baby dirtbike sound, not that loud really.
Ya can check reviews here;
Also while I've not had direct dealings with Dax - I've heard nuthin' but good things about his business practices from everyone who's mentioned him