Hey there - There are tons of aftermarket accessory shops for your 800SX; UTVsource , sidebysidestuff , countrycat , theutvsuperstore and my personal favorite, Ebay... Amazon has some items as well. Just do a google search on 800SX accessories and go nuts. I have installed about every upgrade option you can possibly add on my 800SX TTE (other than hard doors or snow plows) and above is where I purchased 90% of my stuff. I do recommend a folding front windshield if you trailer or drive in the hot summer as it's a welcome relief to have a breeze on really hot days. There is quite a bit of heat that come through the seat & floorboards from the engine and even that can be drastically reduced if you add heat shielding from like DEI powersports... Really like the factory under seat storage as it keeps lots of gear organized, separated and sealed tight away from critters & moisture. A curved light bar across the top will light up your world as well. ..
I will caution folks though if you add a factory heater... The $900+ factory heater is a HUGE pain to install (literally takes 20+ hours) because of the 4 separate plastic 90degree elbows you have to independently align in mounting at the firewall. You get one aligned and then next one pops it off. You finally get 2 aligned, the third pops of 1 or both of the 1st two and so on and so on and so on.... It takes hours, lots of increasing cussing and infinite perseverance to finally get all 4 aligned and THEN you have to carefully ratchet the whole thing up to the firewall without popping one of the 4 off. A couple buddies (Ration your beer proportionately as it's going to take a while), Gorilla/Duct tape will help to hold them in place but again, it still takes hours. I curse the designer of this for making the elbows hard plastic vs flexible rubber as that would make all the difference! After you mount the heatercore/blower unit, you will also find 2 of the 4 duct housings in the kit are too short to reach the dash vent outlets so - plan on improvising in advance or cutting a 2 foot section out of your shop vac to lengthen both a foot. The heater integrates nicely once installed & they work very well but the blower is also really noisy on med or high... Hard to talk over noisy... If I had to do it over again, I would have soundproofed the blower housing a bit before install. I believe an aftermarket Inferno heater would work just as well and install in a fraction of the time for half the cost... Just my 2 cents!
I'd post pics but don't see the option on the menu... Thanks and enjoy!