I have a stock 2011 Rs. Heard about the exhaust fuse pull - what are the downsides? Should I pull?

 

I would do it. My 2012 SS has the butterflies before the mufflers. They are spring loaded, opening only by exhaust flow. I rotated the springs to hold them in the open position.
Yours are electric, and will default in the open position when you remove the fuse. Exhaust will be noisier than it is now at idle.