Last season, I had the opportunity to test and review a 2024 Patriot Boost Pro RMK Slash in the 155” length with the Series 9 3.25″ track. That winter started out slow for all snowmobilers. It didn’t seem to matter where you were from or what part of the world you were riding. I was starting to wonder if I was going to get deep enough conditions to truly test the Patriot Boost Pro RMK Slash package from Polaris. The good news is, Old Man Winter showed up in West Yellowstone, Montana in February. After that it was “game on” for testing and pushing the limits of Polaris’s backcountry mountain weapon, the Patriot Boost Pro RMK Slash 155″.
Sled Specifications and Options
- 2024 Polaris Matryx Pro RMK
- 850 Patriot Boost engine
- 155-inch Slash tunnel
- Series 9 3.25-inch track
- Walker Evans Velocity shocks
Patriot Boost…What a Beast!
Polaris’s Patriot Boost engine is the heart and soul of this package. The elevation I tested and rode at ranged between 6,600 ft (2,012 m) and 10,000 ft (3,048 m) of elevation. At these elevations you can feel the massive horsepower difference from the naturally aspirated 850 and the Patriot Boost. Polaris doesn’t release their horsepower numbers, so we don’t know exactly how much horsepower this engine package is producing. However, Polaris does claim that their Patriot Boost engine produces 50% more power than their naturally aspirated 850 at 10,000 ft (3,048 m). When you ride one of Polaris’s sleds with the Patriot Boost engine package, you can feel how hard this turbo engine pulls at the higher elevations.
Turbo Deep Days of February
In February, the deep snows finally showed up and gave us what my friends and I like to say: “Turbo Deep” days of riding. A turbo is fun every day you ride, but depending on the snow conditions, a rider doesn’t always need a turbo to get to the places they want to go. However, when the snow is “Turbo Deep,” that’s when you’re going to go to places with the Patriot Boost that leave your buddies without that much power behind.
Who Doesn’t Want Extra Horsepower?
Turbos give the rider extra horsepower and track speed with a very little weight penalty. Polaris has done a great job engineering the Patriot Boost engine to be a combination of powerful with a linear and smooth power delivery. This gives the rider the big power they’re looking for in a turbo sled, but in a manageable package, so it’s more controllable and fun to ride.
Patriot Boost RMK Pro Slash…Begging to Be Challenged
The 2024 Patriot Boost Pro RMK Slash in the 155″ length with the Series 9 3.25″ track is by far the most predictable and capable snowmobile I’ve ridden for a whole season. This sled package was begging to be pushed and challenged. All season long this sled kept amazing me; every 
The Pro RMK Caught Me Off Guard
The Polaris Pro chassis is a backcountry weapon, designed and engineered to be precise and perform in the most technical and advanced terrain. When I first started riding this season, the Pro platform felt slightly too planted for my riding style. I like a sled that’s very playful and will sacrifice a bit of performance to have a wilder personality in the sled. But here’s the part that caught me off guard. When the snow got deep, the Pro platform was in a league of its own in the precision category. Moreover, it was extremely playful, especially with the Patriot Boost engine and its 155-inch length. It was a great blend of performance and allowed me to push our limits (the sled’s and mine) on the nastiest of terrain. Having this powerhouse in the 155-inch length also allowed the sled to be playful and fun.
Series 9: The Track to Have
The Series 9 3.25″ track was a beast in the performance department. This track was truly amazing! It provided an amazing amount of traction and lift to my Pro RMK all season. Yes, the Series 9 track helps with the performance by giving the sled loads of traction. But it also enhances the playfulness of the sled by giving it lots of front-end lift.
As an example, on one of the “Turbo Deep” days, I was riding with a couple of guys that had 165″ and 175″ turbos. They were getting stuck in the deep snow in the trees. I would like to point out that I never got stuck once that day. This surprised me a bit, because this sled is only in a 155″ length. I think the overall combination of the Polaris Pro package was the reason I didn’t get stuck. But I cannot deny that the Series 9 3.25″ track contributed greatly. Indeed, it provided a great deal of traction and lift.
Series 9 Track Speed Limitations: What Does It Mean?
Polaris has put a 50-mph (80-km/h) trail speed limitation on all their snowmobiles with the Series 9 3.25″ track. This is meant to prevent overheating, which can shorten its life span. I did, of course, have to test this theory. I wanted to see what the snowmobile would do if I went over that limit on hard pack snow or the trail.
If you go over 50 mph for more than five seconds, the digital screen of the display will show a notification. It’s at the top of the screen in orange and says something to the order of “over speed” or “reduce speed”. Once you slow down below the limit, the notice will immediately go away. What the machine didn’t do, however, was reducing power to limit my speed. That was a rumour that I had heard. The machine might pull power if the speed isn’t reduced after so many seconds, but I’m not sure. I didn’t want to push my limits to test it out and potentially damage the track.
Slash Cooling and Tunnel System of the Pro RMK
The Slash cooling and tunnel system also performed better than I expected. Indeed, the shortened tunnel and smaller cooling system definitely help to reduce drag and snow build up when riding off trail. The first thing that surprised me was how little snow would build up underneath, on the tunnel, while riding. We all know that less build-up means the sled is hauling less weight. A rider will certainly feel that when driving.
The second crazy part is how cool this sled stayed while riding down the trail to get to the backcountry. We don’t usually get it both ways. A cooler sled with less snow accumulation; that’s what I call a win-win, my friends. Even in hard-packed, frozen spring conditions, this combination did surprisingly well in keeping the sled cool. It was way ahead of my expectations.
Backcountry Weapon
The 2024 Patriot Boost Pro RMK Slash in the 155″ length with the Series 9 3.25 ″ track is a true backcountry weapon, capable of conquering the harshest and steepest terrain on the mountain. Not only does this sled want to be pushed and challenged, but it welcomes and embraces all the challenges you throw at it with confidence, grace and power.
What Type of Mountain Rider Are You?
Are you a rider that wants to explore all the sections of the mountain and enjoys pushing yourself by riding the steepest and most technical sections? If so, then you need to take a hard look at the 2024 Patriot Boost Pro RMK Slash in the 155″ length with a Series 9 3.25″ track. There’s a reason this pinnacle of snowmobile performance was my favourite long-term review and is called the Rocky Mountain King (RMK).
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