I have an 09 RZR 800. Was completely stock until I added a 3" lift, new tires (26/10, 26/12), and will be adding doors (UTV Giant) as soon as I get time to get them on. After the lift and bigger tires I noticed some belt slippage in rougher areas as well as a noticeable decrease in top speed (7 or 8 mph) Now I am afraid that with adding doors and thus more weight I will experience more problems with power, torque, and speed. I’m almost positive that the next upgrade should be engine performance. Right?

What should my next upgrade be? Feel free to recommend certain vendors, companies, kits, etc…

Thanks!