that guy from Canada

Most lift kits are simply brackets that move the shocks mounts. 1-2" Up from a arm or down from lower mount, maybe you could fabricate something. Regardless I don't recommend running bigger tires, they take away too much horsepower, that's not there to loose...

More likley a broken clutch spring

Does it feel like its "loading up" with little or no power in reverse? If so it likley needs a new centrifugal or wet clutch, located behind the primary clutch, change the belt while your in there.

Honda is more utility side by side. Can am is more sporty. Both reliable with Honda taking a bit of an edge.

Most atv utv i recommend 10w40 oil, period, but make sure it is JASCO MA2 for wet clutches, motorcycle oil. U can use regular oil but it will burn easy cause of wet clutch and glaze the clutch, causing slippage. Welcome and cheers from the North

Body metal and pop rivets? Ive used panels from old washer dryer or fridge as well.... That sux, probly just crappy plastic

If it only happens downhill engine braking, and riding the brakes stops it its simply a design flaw. If not i would take it back to dealer, could be something else, hard to diagnose unless i could actually test drive it myself.

Hmmm only thing i can think of is that if the rear driveshaft doesnt have a carrier bearing part way down it could be binding when off throttle, downhill under load. Other thought if you are decending steep and engine braking without dragging or using the actual brakes it can be the secondary loading up and banging around. Do a test run on the second point see whats up, if braking helps just brake.

Ok is this a new or used unit?

Welcome! Just a introduction to the offshore brand machines. They tend to be underpowered and high geared for heavy loads or work. Be sure to use low range when working. Also i suggest putting your cooling fan on a direct ignition relay, bypass temp sensor, quad is on fan is on for work. Or you can put fan on a switch, turn on in low range, but you can accidentally forget. These tips will help prevent overloading or overheating the engine Cheers from Canada!

Does this happen in 2wd or 4wd or both

Is it that it has to actually cool off or is it that it simply has to sit a few minutes?

Boss audio has been around a long time... tested n true for a budget system. Its not the best per say but reliable yes. Bang for buck best bet. My opinion

You should never have "a couple of bad ones" pump is good or its not. Likley you have another problem Have you changed the inline filter? Have you fully drained and refilled the tank with fresh fuel? Have you cleaned or tested the injector(s)?

What Andy said is true. Dollars to doughnuts, almost all chineese knock off ATV and UTV are simply underpowered and geared to high. Clutch mods help but best just to use low range gear, be sure cooling system is all good however because you revs will be high and cooling is sub standard, many i have put cooling fan on direct ignition relay, bypass temp sensor, so its just on.