Snowmobile Performance Modifications Simplified

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Navigating the world of aftermarket snowmobile performance upgrades can be confusing. In this article we will look at the various tunerless** performance upgrade options, describe what components those upgrades are comprised of, and compare them on a dollar to horse power ( $/HP) basis.

In the DOLLAR/HP PERFORMANCE section below, we chart out the packages available to the Polaris Axys, Polaris Pro, Arctic Cat M8, and the Ski-Doo Etec. In our summary graphs, we show our $/HP findings and compare the performance increases offered. Silber Turbo consistently offered the best value with the lowest dollar to horsepower ratio.

**For scope of this article we assume tunerless performance upgrades to be performance modifications that are bolt on, requiring minimal snowmobile modifications, and run off of pump gas

What are your Options?

In pursuit of attaining performance improvements and power goals, the industry offers consumers everything from a simple intake or silencer, all the way to big bore and turbo kits. Various companies have combined the most logical pieces to include into one package at an affordable price point. Nearly all the stage 1 and 2 kits do not require the motor itself to be torn down, although some kits do come with things like reeds or a new/modified cylinder head. The stage 3-5 and Big Bore kits may consist of modification to the head, cylinders or exhaust valves. The tunerless Turbo kits we looked at are bolt on and don’t require any engine modifications.

Stage 1

Stage 1 kits will typically consist of different combinations of can, tuned pipe, intake, and fuel controller but nearly all of them will come with clutching. Installing one of these kits will cost you anywhere from around $400 up to $2000 and net you somewhere around 2-18hp, depending on which company you decide to purchase from and your model of sled.

*SLP does have a stage 1.5 kit for the Axys that comes with everything in a stage 1 kit plus a PowerDome cylinder head for extra 4hp ontop of the stage 1 horsepower gain.
Stage 2

Stage 2 kits will normally come with the same parts as a stage 1 but with a few additional components such as reeds, cylinder head, or tuned pipe if it did not come with the stage 1 kit. These kits will run about $800-$2200 and provide gains of approximately 7-23hp.

*A few companies do skip the stage 2 kits and only produce stage 1 and stage 3 kits.
Stage 3

Stage 3 is where most companies provide a kit that includes everything needed to gain the most power shy of enlarging the cylinder bores. This generally includes full pipe, intake, fuel controller, clutching, head as well as some companies go as far as asking you to send in your cylinders, head or even exhaust valves for them to modify per their specifications (such as porting). The kits start out around $1200 up to the sub $3000 range and increasing horsepower anywhere from 9-27hp.
Stage 4 & 5

Often similar to a Stage 3, Stage 4 and 5 kits are offered by companies that have more granular components in their kit numbering, and can include reeds and porting the cylinders in stage 4, and a y pipe and fuel control unit for stage 5. Stage 4 is priced at $2200 for 21hp and Stage 5 is $2600 for the same hp gain.
Big Bore Kits

A “big bore” in sled terms means that the cylinders have either been swapped out or bored out larger to create a larger displacement. This then requires more fuel and larger pistons, more air and more fuel equals more power. Most of these kits do come with supporting mods such as those from the stage kits; full pipe, head, clutching etc. Although be careful and read exactly what is included because some lower cost big bore kits do not include these supporting parts. You can expect to pay between $2200 and $5800 depending on how crazy you would like to go with your motor, horsepower gains will vary depending on alot of factors however claimed is around 20-60.
Drop in/Durability Kits

We did want to touch a little bit on the “drop in” or “durability” kits that are out there as well. These are generally put together to address snowmobile manufacturers little issues in the piston and cylinder department. The past few years have seen these issues worked out but some still want that piece of mind. The kits normally come with everything to install new pistons, some do come with a new cylinder head as well to compliment the new pistons. Cost is between $400-$950 and some even gain up to 20hp.

Turbo charging is a method of forced induction that uses exhaust gasses to turn a turbine, which in turn drives an intake pump to force more air into the engine. Earlier kits had some issues when it came to performance and reliability. The most common complaint was turbo lag, which is the amount of time it takes a turbo to spool up before becoming responsive. Today several companies putting out very reliable, solid and powerful kits that are literally pull and go kits. The kits don’t require a lot of cutting or modifying of the sled and come with everything needed to install in a weekend or even an afternoon. Kits range from $2850-6000+, adding 50-60+ hp depending on what you are looking to do with your sled and the power you would like to make.

Dollar/HP Performance

All the different products that we looked at have stable and reliable products that we would use in the backcountry. For us then, it comes down to reliability, ease of installation and maintenance, and how much performance can be gained per dollar spent. Our pick: in all cases Silber Turbos offer an extraordinary “Tunerless Turbo” kit and by far the best dollar per horsepower ratio.

Here are the details of all the performance packages we looked at, respectively for the Polaris Axys, Polaris Pro, Arctic Cat M8, and the Ski-Doo Etec. Each of the tables lists the manufactures claimed performance increase in horsepower (HP), the list price, the dollar per horsepower ($/HP) and components included, or also required for each performance package.

Polaris Axys Component Options

Polaris Pro Component Options

Arctic Cat M8 Component Options

Ski-Doo Etec Component Options

**The performance numbers and price point are those advertised on product sites or resellers.

Component Definitions


Reed valves commonly referred to as “reeds” are essentially a one way check valve that controls the amount of air and fuel mixture allowed into a cylinder, opening and closing with the pressure changes in the cylinder.
Fuel Controller

A fuel controller is an electronic programmable device that controls how much fuel the motor is receiving based on the custom tune or map that the controller is running. From the factory most machines will run on the leaner side due to emissions compliance. These days most aftermarket fuel controllers come already setup and are simply plug and play. Some turbo kit companies have made it even easier by just reflashing your stock ECU to their custom map without having to add any extra controllers or even having to mess around with tuning your own system, Silber Turbo’s is one of the few companies out there making this happen. As a side note, a “map” or “tune” as most call it is basically; at a certain RPM, the motor will receive a certain amount of fuel. The key is a stoichiometric air to fuel ratio.

When someone talks about having just a “can” on their snowmobile, that would be the muffler or silencer portion of the exhaust system. A freer-flowing exhaust increases the engine’s VE and may up power. One drawback can be higher sound levels.

The tuned pipe, that is the enlarged/bloated looking part of the exhaust that is basically an expansion chamber used to improve its volumetric efficiency thus creating more power. A “full pipe” would be a combination of the pipe and can.
Y Pipe

A Y pipe, is the part of the exhaust system that bolts between the motor and tuned pipe, joining the exhaust gases from both cylinders.

Clutching may be one of the more complicated items of the whole job. You can have the fasted sled on the snow but if you’re clutching isn’t right, a lesser powered sled will pass you up in no time. Most clutching kits come with a new primary clutch spring and secondary clutch spring as well as new cam arms commonly known as clutch weights. The combination of these items allows you to play around with peak rpm for that perfect peak hp, how quickly the engine can accelerate as well as back shift.

Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve the quality and quantity of the air flow. Cylinder heads, as manufactured, are usually suboptimal due to design and manufacturing constraints. Porting the heads provides the finely detailed attention required to bring the engine to the highest level of efficiency. More than any other single factor, the porting process is responsible for the high power output of modern engines.

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