I asked that question about a new 610 I purchased and I received Zero replies. After looking all over the net I found 1 person that said he was happy with the add on and another couldn't tell the difference. I put one on a Rhino450 and it made it a lot quieter outside of the cab but very little if any difference inside the cab. I would expect the same for the Mule. If your Mule is older and the muffler is louder than the newer ones it may help.