FMF Q will it really make a difference?

My street bike is a 'oo yamaha 426. And it is louder than H E double hockey sticks. Currently it has the stock muffler,repacked with strand type packing. I can get a Q muffler brand new for $100 off retail . will it make a difference ? or should I make a small baffle for the inside of my stock muffler. I also do not want to loose any power ,as if that is not to much to ask for,to shut the thing up a little.