Stock intake still doesn't work so hot in silt, even with a pre filter. I have a uni filter too, but have yet to run it. I keep it for an emergency back up. My dad has a knn setup on his RZR800 and it's a PITA to service. I stay stock air filter, if I was gonna change it would likely be a dry media filter from AFE.
I'm running the Big Gun Exhaust, it's loud. But I like loud. YouTube video online, google Team Pistelak Exhaust