My y pipe is my only exhaust upgrade. I was thinking about getting a b pipe but leaving stock muffler. What advatages would this give be? WHat disadvantages are there with this setup?

 

That is exactly what I did. The advantage is that you get the extra few HP yet keeping the overall sound down, and the stock muffler along with a y-pipe and b-pipe sounds very good. Deep and low.

Disadvantage, if you could even call it that in this case, is that you are missing out on a few more HP by not getting a higher flow muffler. But that is a small enough difference that it is negligible.