In the sport ATV world live primarily three types of riders: The Racer, the Recreationalist and the Duner.
All three ride pretty much the same style of quad but each chooses different preferences when it comes to upgrades. (A fourth type of ATV rider sits on the Utility ATV which scales back on the starting line punch but brings horsepower for jobs around the farm and utilizes a much different set of parts.) And, like all machines, eventually parts wear out giving the owner an opportunity to save money while installing a better performing, and in most cases, a better feeling product.
Thus, while all three varieties of ATV owners generally require and favor one type of tire over another (i.e. paddle vs. racing tire) certain upgrades cross the style line making it easier for us to provide across the board recommendations on where to upgrade for those on a budget. Besides, most ATV owners have more than one quad to tap into the variety of fun opportunities ATV riding offers.
So whether you race ATV MX, or love the dirt or sand trails, you can forego any expensive exhaust or suspension system and focus your hard earned dollars on Controls. Smoother and more comfortable riding tends to help with speed for the track and longer more enjoyable rides on the trails.
Bumpers
Whether you race or enjoy a more leisurely pace on your quad, bumpers protect you and your ATV from other riders and obstacles. Unlike a car, expect your bumpers to get used and abused which is why you want something durable that stands up to the rigors of ATV riding without spending a fortune. Check out the Rock Racing Front Bumper that racers should especially appreciate thanks to the added (make that subtracted) weight savings.
Grab Bars
A grab bar serves several purposes, first and foremost, it gives you the ability to pick your quad up from the rear and it also acts as a bumper. For dune riders, most grab bars offer a mounting point for the required orange visibility flag. Check out the Rock Sport Series Grab Bar, like its front bumper cousin, this one is constructed with the same durability without adding significant weight.
Nerf Bars
You simply cannot ride an ATV without nerf bars - at least not very effectively and certainly not in racing. Even a non-technical trail ride turns exhausting if your mind and body is focused on keeping your feet on the pegs. Grab a set of Rock Standard Nerf Bars and enjoy all a quad offers.
Levers
Shifting gears and braking. Pretty much what you're doing the entire time while riding an ATV. So if you're using levers that don't feel right or worn from overuse, it's time to upgrade. Check out the series from ASV or Streamline and stop abusing your hands and fingers.
Grips
Like levers, a bad set of grips can mean the difference between powering through a Moto or riding all day on the trails verses a flair up of blisters or using all your strength to hold on. Grips need not cost a wallet's full of money, grab a set from ODI or Torc1 Racing and enjoy the comfy softness along with a solid grasp.
Brakes
Whether you race or use a quad for recreational purposes a great set of brakes can certainly make or break your ride (no pun intended!). Racers already know in order to go fast they must learn to go slow, so grab a set from Galfer or Streamline for durability, strength and a bit of style.
Exhaust
You can certainly spend the money on a high-end complete exhaust system and if you're racing Motocross and have a line of sponsors, that's usually when it makes sense. But for most people looking for notable power gains, along with a nice throaty sound and some added character without raiding their retirement fund, a slip-on from Big Gun or HMF answers the call.
Depending on the make and model of your ATV, you can upgrade every category listed here for about $1000. Once you feel the difference the track become less intimidating and the trails turn into your own wonderland.