I've owned this bike just over 2 years, and I've had this set up on it for over a year...
I've put about 15K miles on it since I changed the pipes. And I checked and made sure that there is not an obstruction in the pipe.
Yes it does get a little louder when I stand behind the bike, but that makes it quite difficult to ride that way!

 

For some reason your op read like you bought the bike 2 days ago. Two posters above seems like they read it that way too. My mistake unless there was an edit. Check the pipes for a bbq 'd mouse or 2 but it looks like you already did.

 

I thank everyone for the suggestions, but Wilburcat hit it right on the head. I found both nuts for the rear pipe to be about a quarter turn loose, tightened them and it's back to normal.
Again Thank you.
RainMan