Making it look as great as it works By the staff of Dirt Wheels

Travis Gardner’s Kombustion cars are always showpieces, and this RZR Pro R 4 Premium is no exception. They are never parking-lot queens. He is always ready to drive them hard.

Salt Lake City-based Kombustion Motorsports has built a long list of impressive machines. It seems like company principals Travis Gardner and Ryan Flanders are constantly building new machinery. This time, though, Gardner got a major holeshot with the hot new Polaris RZR Pro R 4 Premium. The Pro Rs were barely out when we caught Gardner’s full build at the Adventure Rally on the Rocks at Sand Hollow State Park. Gardner admitted that this was the fastest he had ever completed a full build.

In the past Travis had been inundated with folks trying to buy his builds as soon as they are completed. Many times he goes along with the sale and on rare occasions before he ever even had a chance to use the car himself. We have a feeling that this Pro R 4 will stay with him awhile—at least until they are a little easier to come by.

Sand isn’t really a happy place for the EFX MotoRally tires. They work great for minimal pavement use, rocks and the hard dirt found in Utah. Packard paddle tires take care of sand trips.


When you have a shop that produces modified UTVs, and you have the products and connections to make it all happen in a hurry, you sometimes look at UTV shopping in a different way. There is no doubt that Gardner could have started with the RZR Pro R 4 Ultimate with the computerized Dynamix suspension, but he didn’t. In fact, we don’t think we have ever seen him with a Dynamix car. He always has plans to dial in and personalize the suspension on his builds. In his mind it doesn’t make much sense to start with Dynamix if you are planning to change things.

Even with hard-terrain tires, the RZR Pro R 4 was capable in the sand. More than 225 horsepower on tap will make sand doable no matter the tire choice. The chassis loves the dunes.

In this case there was no need to replace the stock suspension arms. People change suspension arms to make the car wider, lengthen the travel and to gain stronger components. The stock Pro R arms are light, strong and already have a 74-inch width.

At present the new toe link in the rear trailing arms makes it difficult to have arched A-arms. For some types of obstacles that can be a problem. Time will show if anybody can solve the problem.

The carbon hood, glass windshield, Heretic lights, and Assault center and exterior mirrors all add to the rich and luxurious look of this Pro R.

Regardless, Gardner chose to purchase the RZR Pro R 4 Premium to have Ride Command and factory-integrated audio. For shocks, the Sport and Premium versions have Walker Evans 2.5-inch needle shocks in front and 3.0 shocks in the rear. Before we experienced the machine it already had a ZBroz spring kit, but for the most part the suspension was stock. It was our first experience with the Walkers on a Pro R, and the feel and action were quite good.

Gardner had the car fit with stunning Metal FX beadlock color-cut wheels and monster EFX 37-inch MotoRally tires. Sand Hollow terrain makes abrupt transitions from light dune sand to rock fins and ledges that are brutal obstacles. Kombustion’s Pro R 4 handled those transitions in style. We have no doubt that the 37-inch tires with deep sidewalls and larger rolling diameter aid the suspension feel. Polaris puts 32-inch tires on 15-inch wheels for the Pro R, and Gardner stayed with 15-inch wheels, so there is a great deal more tire sidewall to help absorb bumps. Still, the suspension worked very well.

This is just the takeoff from a dune climb at Sand Hollow. Things just went up from here. The Pro R landed just fine. The new Polaris suspension truly works well to control the car.


Some of the choices that Gardner made were not specific to his business. Utah allows a limited license plate for UTVs. They cannot use highways but can use secondary roads to connect trails. That is why this Pro R 4 employs the EFX MotoRally tires. The tread pattern lasts well on the street, and works excellent on packed dirt and rock. Performance on sand is limited, especially on the wispy sand at Sand Hollow. For that reason, Gardner selected Method Race Wheels beadlock wheels with Packard Engineering Sand Light tires for when he chooses to spend time in the sand. It is a simple matter to swap out wheels. With the two sets of wheels, the Pro R 4 performs on any terrain found in the western states.

We were surprised that the Pro R 4 worked so well with the giant tires on it. It does have an Ibexx clutch kit, but it never feels like the gearing is too tall in high range or low range. It crawls the truly ugly and steep sections of slick-rock trails in low range with ease. Even with the significant ground clearance boost from the 37-inch tires, Gardner further protected the underside of the car with a full Trail Armor UHMW plastic skid plate with rock sliders to protect the lower edge of the body. The Sliders are available with outer surfaces that are a different color from the main plastic. These sliders are white UHMW plastic with a thin layer of black on both sides. It makes for an interesting look. The final performance mod was a tune from Evolution Powersports.

Builders that really want a car to stand out frequently select the contrast-cut wheels from Metal FX. The wheels are machined, anodized then machined again to remove some of the color.


It seems odd to start talking about the SDR Motorsports roll cage as part of the revision of the interior space of this Pro R. The Fastback shorty cage changes the look of the machine, in addition to enhancing the safety. A variety of options to go with the cage certainly qualify. The look is changed more radically with the addition of SDR Hi-Bred front and rear doors. These doors smooth the lines of the machine, making them ideal for the colorful Envision wrap. The door’s inner sides look luxurious and finished with Hi-Bred door bags for all four doors integrated with SSV Works door speaker pods and speakers. SDR’s full-glass windshield gives the cab a nice, finished feel as well. Outside the car SDR contributed a front winch bumper (fitted with a 4500-pound-rated SuperATV winch), a front grill kit and a rear air-intake grill kit.

Luxury truly ticks up with four Simpson Pro Sport UTV seats with the heated seat option added. Gardner selected a striking color combination of red, white, blue and silver with a handy pocket on the seat fronts. D3 harness belts in 2-inch black in the rear and 3-inch black in the front contrast nicely. Each belt has a comfort pad with the Simpson logo on it.

SDR’s Hi-Bred doors are very sleek, and the Hi-Bred door bags and SSV Works speaker pods give the inside of the doors a clean and finished look. Latches are stock Polaris.


Joining the SSV Works door speaker pods is an under-dash subwoofer enclosure designed to work with Ride Command. There are also 8-inch cage-mount speaker pods in the rear. Everything is boosted by a Phase audio five-channel, 800-watt Ride Command integrated amplifier kit. All the SSV equipment comes with plug-and-play wiring harness to streamline a reliable installation.

Fourwerx Carbon is best known in Dirt Wheels for Honda TRX hoods and seat covers, but this Pro R has a three-piece carbon fiber dash trim kit, a carbon Ride Command surround, and a V2 carbon fiber hood. A Viper Machine shifter in blue matches the seats and further separates the cockpit from the ordinary. Viper also added a billet rear radius rod plate with a tow loop.

There is a lot of nice detailing to the car, including Heretic Studios lights controlled with STV Motorsports illuminated blue LED rocker switches. There is a Ryco Motorsports street-legal lighting kit with horn and turn signals. Kombustion tied everything together with 54 hours of labor from the tech staff. Kombustion handled the powdercoating and arranged for Envision to lay down that sweet wrap.

Left: Assault’s new Nighthawk side mirrors incorporate a quad light angled to the side of the car to illuminate turns. The small light on the windshield is just one of multiple Heretic Studio lights.


Polaris’ Pro R 4 is a large machine, and it feels even larger with 37-inch tires on it! Nevertheless, this Pro R 4 has a luxurious feel and rich look that we rarely see in UTV builds—even less so in builds that come together in a time window as compact as this one did. How does it perform? Simpson always makes an interior a nice place to be, but that feel is furthered by the padded door bags. We already mentioned how impressed we were with the ride with the 37-inch EFX tires. This whole machine looks and rides great with massive performance. Drop the speed, slip it into low range and it will handle tech driving with the best.

We talked with an aftermarket product company owner who said that he had decided to pass on the Pro R. He couldn’t see spending over the retail price for a machine to develop parts. A five-minute ride in this Kombustion Pro R 4 was all it took to make him re-evaluate. And, that ride was in the sand. That is arguably the least impressive surface to experience this Pro R 4 on with the hard terrain and rock-specific tires on it! It is that good.

Travis Gardner claims that when he bought his first Polaris RZR 900 he was obsessed with it. He found any excuse to get out and experience it. He says that he hasn’t had that feeling with other new machines until this Pro R 4. No Pro R 4 is cheap, and this beauty is anything but; however, Travis Gardner would do it again in a heartbeat. But, he isn’t planning to. So far, this one is not for sale.

The monster 37-inch EFX tires look normal on the Pro R 4. Viper makes the billet radius rod cover with tow loop. ZBroz Racing already has a dual-rate spring kit for the RZR Pro R 4.


5150 WHIPS: (866) 511-8853, www.5150whips.com

Dome light RCA plug: $85

ASSAULT INDUSTRIES: (714) 799-6711, www.assaultind.com

Nighthawk LED side mirrors: $799.99

Bomber convex center mirror: $99.99

On-the-go tool kit (metric): $349.99

EFX TIRES: www.efxtires.com

MotoRally 37×10 R15 tires: $1,628 

(set of 4)

ENVISION: www.automotivepersonalized.com

Custom graphic wrap: $3,999.99

EVOLUTION POWERSPORTS: (715) 247-3862, www.evopowersports.com

Pro R performance tune: $749

FOURWERX CARBON: (262) 501-9696, www.fwcarbon.com

Polaris RZR Pro carbon fiber dash trim kit (3 piece): $365

Polaris RZR Pro carbon fiber ride command surround: $185

Polaris RZR Pro V2 carbon fiber hood: $295

HERETIC STUDIOS: (801) 725-4824, www.hereticstudio.com

6” LED light bar: $219.99

BA-2 LED light pod: $659.94

Quattro LED pod light: $269.98

30” LED light bar: $749.99

IBEXX: (208) 352-3045, www.ibexx.com

Clutch kit: $599

KOMBUSTION MOTORSPORTS: (801) 674-2451, www.kombustionmotorsports.com

54 hours labor: $6,480

Powdercoating 4-seat cage: $595

Powdercoating 4-seat roof: $127.50

Powdercoating front bumper: $110.50

Powdercoating grill insert: $59.50

Powdercoating grill/frame/logo: $110.50

Powdercoating windshield frame: $51

Kool Whips 5-foot Bluetooth whips:$399

METAL FX OFF-ROAD: (714) 891-7684, www.metalfxoffroad.com

Delta R monoblock forged beadlock wheel: $3,599.96 (set of four) 

METHOD RACE WHEELS: (866) 779-8604, www.methodracewheels.com

413 Forged 15×7 beadlock wheel (polished): $1,620 (a pair)

413 Forged 15×10 beadlock wheel (polished): $1,726 (a pair)

PACKARD PERFORMANCE: (801) 335-4013, www.packardperformance.com

Sand light front tire: $554 (pair)

Sand light paddle tire: $646 (pair)

RYCO MOTORSPORTS: www.rycomoto.com

Polaris RZR Pro XP turn signal/horn kit with headlights: $535

SDR MOTORSPORTS: (800) 277-2280, www.sdrmotorsports.com

RZR Pro R 4 Fastback shorty cage: $3,083.99

Full glass windshield: $679

Pro R front winch bumper: $425.99

Pro XP 4 Hi-Bred door storage bags: $189.99

Pro XP 4 Hi-Bred full doors: $1,599.99

Pro XP front grill kit: $189.99

Pro XP rear air-intake grill kit: $139.99

SIMPSON RACE PRODUCTS: (800) 654-7223, www.simpsonraceproducts.com

Pro Sport UTV seats (four): $2,519.80

D3 harness 2” with pads: $279.90

D3 harness 3” with pads: $299.90

Heated seat option (four): $679.96

Seat front pocket option: $279.98

SSV WORKS: (818) 991-1778, www.ssvworks.com

RZR Pro XP front door speaker pods, speakers and plug & play harness: $459.98

Polaris RZR Pro XP rear door speaker pods, speakers and plug & play harness: $459.98

Polaris RZR Pro XP under dash subwoofer enclosure for Ride Command: $999.99

Universal 8” cage mount speaker pods, speakers, clamps and plug-and-play: $619.98

Phase audio 5 channel 800-watt Ride Command integration amplifier kit: $899

STV MOTORSPORTS: www.stvmotorsports.com 

Backup lights blue LED rocker switch: $29.95

Bumper light blue LED bar rocker switch: $29.95

Interior light blue LED rocker switch: $29.95

LED light blue LED bar rocker switch: $29.95

Lighted whip blue LED rocker switch: $29.95

Rock lights blue LED rocker switch: $29.95

Side lights blue LED rocker switch: $29.95

SUPERATV: www.superatv.com

4500-pound winch with wireless remote & synthetic rope: $414.95

TRAIL ARMOR: (662) 462-4222, www.trailarmor.com

Polaris RZR Pro R 4 full skid plate with standard black/white/black sliders: $1,525

VIPER MACHINE: (435) 789-7463, www.vipermachine.com

Polaris RZR Pro R ultimate shift system (custom color) (801) 674-2451: $639

Pro R radius rod plate: $225

XTC POWER PRODUCTS: (480) 558-8588, www.xtcpowerproducts.com

Polaris RZR Pro XP 6-switch power control system (switches not included): $299

ZBROZ RACING: (435) 753-7774, www.zbrozracing.com

Pro R dual-rate spring kit: $995

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