I have a 2021 Uforce 600 with the full cab and hard doors. The noise level inside is absolutely ridiculous to where you have to yell almost scream to talk. I have installed two layers of sound deadening material on the floors, kickboard, completely behind the seats, the storage boxes, and the roof. I even installed an overhead stereo which I cannot hear when I'm driving my 600. I'm at a loss on what to do now. My next move I'm thinking is to install sound deadening material on the rear poly window because it sounds like some of the noise is coming from it but it's not vibrating to the touch when I drive. I've also bought an exhaust pipe silencer to try to see if that helps. I know it's transient vibration that is flowing through something but cannot figure out where. Anyone have any ideas? Thank you     

[2015 Z Force 800 53/Trail EPS]

Check the engine mounts. CFM uses a rubber mount system (assuming the 600s are the same) that in some..has come out making the engine rest loosely on the steel sleeves...and make a lot of noise. There are also several reasons for the front drive lines to generate noise. See if its any different between being under power with and without being in 4WD.

Engine mounts are all good. I'm thinking as a lot of people have stated that it's just the single cylinder design that makes it so loud. Trying to find maybe a waterproof and high temp sound deadening material I can install under the bed and on the outside of the rear seat panel over the motor.   

Unfortunately I don't think it's just the single cylinder design. My 800 is loud as crap. The wife said it's too loud. Honestly we just got used to it. My friend has a Kawasaki teryx 4 seater. He installed a windshield and rear window. That machine is crazy loud now. I think it has more to do with the full cab.

[2015 Z Force 800 53/Trail EPS]

I always thought my Z was way too loud even after all I had done to cut the noise down but then I had the chance to ride in my friend's A/C Wildcat Trail and I was deaf after about 10 miles. I was never to happy with my Z's noise levels after that. Of course my other friend's RzR 800 is quieter then mine..of course..