Product Details



The best engine and exhaust components in the industry for the new Polaris 850 & 900r twin. With over 600 dyno runs on this package I'd say Terra Alps Racing has a kit for you.

We started designing our 850 patriot products early in 2018 before the sleds hit the showrooms.

Also building the first 840 stroker and 900+ bigbore stroker in 2015' We have a few years on it.


Want to beat your buddies new Polaris Boost and Doo Gen5 turbos? ya we thought so. Our Polaris 850 with Terra Alps performance kit likes beating turbos. Yours can too.


Latest rage seems to be the new 900r engine. Well it builds more mid range power but falls short on top end with 4 hp gain on top end over the 850. The 900r gets a good improvement with the Terra Alps billet head. Especially for high elevation riders. Porting is also a good benefit as the production engine is still a production engine. Terra Alps muffler is also an improvement over stock and other mufflers in the industry. Give Terra Alps a call or email to get the improvements you need for your 900r


850 & 900r PERFORMANCE KITS - We have a wide range of tuning for the 850. ECM Performance reflashes for stock or performance editon kits from Terra Alps. With a mufffler combo, billet head with different dome arrangements. Then can step it up with a Y pipe, porting or the top dog the 929 Big Bore!


Porting cylinder 850 & 900r  $800 cdn. or $600us

Billet head with custom domes for multiple applications $699 cdn. or $515 us

ECM performance tune $649 cdn or $479 us

Y pipe 6 hp gain $399 cdn

Muffler 5 hp gain $399 cdn

This package gained 24 hp or 16% peak on a 2019 850 (stock 148.5 - 172.5hp on our dyno) pump gas


ECM Performance reflash capabilities for Horsepower gains. To get better running conditions, more consistant passes back and forth down the lake, on the mountain climbs, blasting down the trails with HP gains for stock sleds or with performance mods. More importantly to work with the add-ons you have. $749 cdn. or $540 us approx.

Can also do custom tunes, email to discuss. With over 600 dyno runs Terra Alps has proper designed tunes unlike others guessing.


929 BIGBORE from Terra Alps Racing, you wanted something bigger thats what we thought! This kit makes great gains from botton to top end gaining 25+ hp or 18% gains on our dyno at peak. The mid range is strong gaining 12-15 hp or 11%+ gain depending on pipe at 7000 rpm before the exhaust valves open. Thats grunt!

ALOT of work went into this bigbore to get the power you would expect. I tested stock bored out cylinder like others kits that made very little gains, like almost none! Then added bit more everytime to get where we need to be. It takes alot of work to make 20+ hp with single pipe and Y pipe combos on todays sleds that are making good power from factory.


929 bigbore Kit includes boring, welding and modifications to reinforce the cylinder for large power gains and reliability, full out porting of cylinder and cases. Kit comes with 2 piston kits, billet head with Terra Alps unique domes to run pump gas at your riding area, exhaust valves get machined for proper operation and airflow.

Send in your cylinder, cases and exhaust valves complete, or complete engine. $3195 cdn. or $2400 us approx.

ECM flash needed $649 cdn.

High flow Y pipe $399 recommended

Muffler $399 cdn. recommended

Adjustable clutch weights $349 cdn

Single pipe $749 optional

900cc kits also available for class racing

email terraalps@shaw.ca or call 1-778-753-6060 for more info


If you have a 900 so called bigbore from a dealership dont think its a full build making 200 hp! Your lucky if its making 5 hp gains. Yes there that bad. Takes alot of work to get real gains and these so called big bores that are just bored out and replated with no porting, no proper head design, exhaust valves not machined properly, nothing special are wasted money.


The new 2023 900r similiar to the 850, little more porting and some exhaust changes. With 4 hp gain has good throttle response is similiar in power to other bored out 850-900 we dynoed. Seeing some gains. But still no 929 big bore power gains. 


BILLET HEAD with interchangeable domes for 850 and 900r, gain 5 hp for low elevation. Gain 7+ hp for higher elevations. Gained 250-300 rpm in testing over stock head on 2019 850. Add 2-4 grams of weight to primary clutch. Proper cooling in head with turbulence to pull extra heat away from domes.  $649 cdn. or $520 us approx. 

Best performance gain for high elevation riding!

Multiple Compression ratios available for your riding area with pump gas, low or high elevation riding, race set up and turbos.

Set up for your 850's timing curve and exhaust pipe.



MUFFLERS - Narly lightweight and gain the most power of any muffler! we dynoed them all. For stock and our highflow bigbore kits. Can acheive up to 10 hp gains. We spent alot of time developing this muffler, lots of dyno time, to get the power and right sound, not too loud. Its whats inside that counts.

Mtn Narly edition Deep Raunchy sound, but not ear bleeding 5 hp gain and saves over 10 lbs $399 cdn. or $320 us

Trail Muffler, quieter then the MTN muffler, bit louder then stock   $399 cdn. or $320 us approx.

Stock 850 muffler is 16 lbs.

Cooking Muff pots available on Mufflers on request. $79.95

Muff pot mounts on Muffler $140



HIGH FLOW Y PIPE $399 cdn. or $320us Gained up to 6 hp with our ECM performance tune.

High flow for our porting kits and needed for bigbore 929 kit


CLUTCH KITS are needed as were making HorsePower!

Our primary clutch weights load like no other, normally 8 gram less weight doing more work. Doesnt feel like a large mass weight to hold back that extra horsepower werre building.

We have a wide varity of clutch springs from most manufactures.

Custom Terra Alps Helix's and standard helixs available.


PORTING - cylinder porting on 850 $600 cdn. gain 10+ horsepower top end charge

Case porting $250 cdn.


TWIN PIPES !  2019 & current 850 RMK chassis $2099 cdn or $1520 us approx.

Trail models Indy, Sks, Switchback assault with straight steering posts $2199 cdn or $1590 us approx.

comes with brackets, springs, and hardware


when we have time, when its slow.

Custom for our bigbores and our best clients.


126 mph in 1500ft, 114 mph in 1000ft, 105 mph in 660ft, with Terra Alps 850 performance kit! in winter of 2019' pump gas.