there is a few companies out there making exhaust for the rhino but more so catering for performance, and in turn you might be forced to start playing with the jetting. I did not see a rhino exhaust on the HMF website, i know they do have lots of utility ATV exhaust, but nothing for the rhino. your cheapest bet would be a factory take off, find those on ebay and what not. it will be the quietest and least hassle .
heres a good website on all available exhaust kits, most with dB ratings