Best pipe with stock silencer

No aftermarket pipe will perform well with the stock silencer unless you removed all the baffles and convert it to a packed straight through design.
 
My dad says that he wants it quiet. I wish I could have a full system though :(
With an aftermarket expansion chamber the stock silencer is actually louder than some aftermarket ones. The Fmf seams to be the quietest and it also would be a great exhaust for trail riding.