IF you have any comments or experiences using our products... PLEASE send us your testimonials...

 We will publish it here with your name under it.

Hi Kelsey

      I thought that I would send you a quick message thanking you for the great sales advice  and product when I purchased my new Wossner produced pistons.

for my ’13 Polaris Switchback 800cc last fall. We had a short 6 week season here in Eastern Ontario, Canada but I enjoyed every mile (3200) on the new pistons. What a difference in performance over the OEM pistons. I followed your break-in advice and adding extra 2 smoke oil to the 91+ fuel on fill ups,  plus following your warm up procedure instructions. This has been the best investment that i have made for my sled and cannot wait for ‘15-‘16 snowmobile season.

 Take Care

Dave C.


Thanks for the new found power flat out walks away from my buddies slp kit. The question i have is the sled will over rev and hit limiter out of the hole I did add 4 grams over in the clutch . How do i get quicker up shift with out losing rpm on the top on long pull i get 8050ish for rpm. When i went 2 grams lighter it hit limiter easier but it pulls 8300 ish on long pulls just bumps limiter .Running non-ethanol 5k and up for elevation. Do the make a kit to eliminate the rev limiter or change helix and springs. Thanks In advance Paul     sled is all stock -your motor



As the 2013 season winds down, I wanted to drop you a note of thanks and mention how satisfied my riding buddy Mike and I are with the 670 dual ring piston rebuild we implemented on our 500ss engines along with your billet heads.  
Our 500ss engines have never sounded or performed better ...it was a little extra work, shimming the cyls/deck height, but at this point I'm very pleased with the results.  We started slow, way on the fat side ... our mpg is currently what I would call safe @ 13-14ish, but now near the end of the snow season in Maine, both sleds run awesome!  
Tim Nevins



We have spent a substantial amount of time and effort trying to quantify real world power gains on naturally aspirated RMKs.

Driven largely by a genuine need to find a desirable compromise to boost, its been a somewhat frustrating venture.

Many kits we tested did indeed produce results, some with impressive gains in throttle response and midrange punch but fell flat on the big end, others just making noise, however when weighed against the dollar investment, most left us feeling slighted...

Though I have no question some of these indeed perform well at other altitudes as advertised, they just didn't show well with our use demand and altitude.

Various configurations of porting, heads, pipes, silencers, pistons (even cat pistons), clutching, timing, fuels and fuel controls have all been rendered down to one true stand out.

Though I can only speak to our test results, which are all done at 9500'-13000', the RKTek Drop in kit is with a doubt the best bang for the buck...

Our testing showed the 13 kit produced impressive gains in loose snow track speed, as well as significantly better throttle response and power across the spectrum.

Though this package does require a fuel control (13 model), it is very easy to tune, it is also very easy to clutch, and is rock solid consistent.

We will be doing follow up testing with different exhausts applied to this kit soon (preliminary testing shows great promise), and also a real world evaluation of the RKTek big bore for the RMK 800 as well.

Seldom does such a reasonable investment produce such a dynamic result.

Just thought it worthy of mention as many of you have inquired about such kits...

Eric Woog VOHK Performance Kremmling CO


I purchased and installed one of your drop in kits for the Polaris 800 dragon.  I know you haven’t done testing on the 2009 Dragon but I’ve been testing it and have found it to be very rewarding.  The cooling is at least 15 to 20 degrees cooler than it used to run and I needed to install one step hotter plug.  The throttle response is amazing.  It develops power way sooner than before and holds torque all the way through to top shift at about 8150 or 8200 RPM.  I am thrilled with the performance and couldn’t be happier with your product.  A friend of mine who owns a 2013 Pro rode on it and couldn’t believe it “Spanked” his sled.  He liked the way it pulls hard all the way from about 6000 RPM or so.  I am recommending your product to all my 800 Polaris rider friends.  Mitch Hartley Nampa Idaho




Good Morning Kelsey

Your heads are a definitive plus and a advantage for my application and team.

Starting at 131 hp with SkiDoo Mod spec for this season, it is very difficult to go over 136 corrected hp on our dyno results.

Changing timing configuration, bored carbs, race fuel recipes and/or tune pipes does not add any hp. We feel it is top there.

Adding your heads, is another story. On my 2 Mod sleds, we finished w 140hp and 144hp on the second one. Every legal modifications we work with shows a result and improvements. Sounds is way different and healthy, combustion and spark plugs

are clean.

Response of the power on the track is a big plus too. This weekend in Plattsburgs, I had the fastest sleds from far!


Luc Brunelle






have roughly 50 miles on my 2013 155 pro with kelsey's drop in kit with the higher compression head. I have "stacked" his set up with an slp pipe can power commander and my own clutching (not slp's set up). It is a noticeable difference. as far as track speed i do not know yet as we only have about 2 feet of snow right now. what i do know for fact is that with this set up running the slp stage 4 map which is def. on the rich side i was able to quite easilly beat a 2012 stage 4 slp pro 800 in a short drag race. not only that i am pulling 2 grams heavier weights than the same set up with out the drop in kit. and i'm pretty sure i'm going to have to add even more weight. the power band feels much SMOOTHER and it even gives the motor a lot crisper sound. I am sold on these kits so far after a little bit of experience around kelsey's product last year and this year. Lets just say that mine ran good enough not even broke in that i have already sold 7 more of kelseys drop in kits. Eric Woog (owner of VOHK) is also running these kits and he def. knows what he is doing when it comes to making power on sleds.


Hey Kelsey. Put my drop in kit in today, nice stuff. On this sled also all the annoying vibrations and 3000rpm death-shake are gone. Smooth. The stock pistons were 3 grams different in weight. The wossner's were a full 27 grams lighter and exactly the same weight to the gram. The old setup when idling the coolant temp would gradually climb of course and continue to climb without hesitation. Your head cools so efficiently that i never could get the temp over 133F it would just sit there. Even when brought up to 4500-5500 rpm the temp would slowly climb to 140F. What an amazing difference. Can't wait for good snow now. Turned the oil pump up one full turn and running 91 octane on the non eth resistor. 1/2 litre of semi synth oil in full tank fresh fuel. Anything else you think i should know bud shoot me a pm when you get a chance, i know your flat out. Have a good one man.
Thank you,


Kelsey just a line to let u know how my 860 is running had it out for four days in the hills and it ran strong clutching still a little off but could give an ETEC a head start and pass him before the top and could only get to 3/4 throttle this thing just don't stop pulling thanks for all your help and good work

Hi Kelsey,
Just finished redoing the top end and used your dual ring pistons and very nice anodized head. The shape of the dome compared to stock is fantastic and there is no wonder why this set up would make more power and be more efficient. What was BRP thinking when they designed that head and a single ring piston? I had plenty of blowby on my old pistons. With the new pieces installed, it sounds great and has a snap to it, not like before. I am in the process of doing a quick break-in time on it but I can already feel the power far exceeds what I had in the past. Thanks for the great product and quick shipping!
Tim Ljuden
Grande Prairie, Alberta 





Hey Kelsey,
I just wanted to give you a mid season update on my 700-800
bigbore. Freakin phenominal is all i have to say, you did your homework. It flat rips and hasnt missed a beat in 650 miles. All my buddies cant figure out what to think when i blast by them. Im totally impressed with your work, and you will continue to have my business.



Just thought I'd give ya a little update on my sled. I have an 08 800r with your 13.1 head, porting and ecm remap. I just did a full rebuild crank and with brp pistons, had a dealer credit on them so didn't cost me anything. Running 8hole base and squish at 48 thou and 450 mains. I was on the lake here today against a shr 840 with twin dmax pipes and he tried all he could and I was consistantly faster. I have more to gain as I was consistantly seein 8400 on the digital so lil more flyweight and I'll pick up some more. Just wanted to give a little credit where credit is due. Thanks for the solid and reliable HP. Jesse


Hello Kelsey and warm greetings from Finland!

It has been one great winter. Both our group RKtek´s have been running without a problem and VERY strong (been comparing them to 800etecs and no problem to outrun them!). I counted that I´ve run 600l on gas with this thing and absolutely love it! Still one trip to go into swedish mountains, lets see how it runs over there.


just thought I would give you an update on the kit I bought from you. The thing runs so strong I am having a hard time keeping the front end from coming to far off the ground. That is with toms evolution rear skid. but must admit its a good problem to have. Thanks for the great product.

Jason Johnston
Soldotna, AK


just wanted to say thank you again for your help.  oil pump was at 22 which we didn't even think of checking...lesson learned after a sled goes down to check everything, not just the obvious.  sled runs absolutely awesome, tons of power and am just thrilled with it.
thanks again for your help and for an awesome kit to make this doo run like a champ!
Brian Heringhaus


Kelsey, I could not be more happy with the head you sent me for my home brew f7-f8 kit. looks as new still and performs perfectly. The 03 f7 used to have a problem with the heat light flashing under a lot of conditions, it has never come on since installing you're head. Performance is superb, but I have been accused of having nos on the sled since putting the kit in lol,  again many thanks. Michael Fitzherbert




I am so impressed with this thing...we took them up MT. Baker this last weekend and were out climbing the few turbo dragons we encountered...Bad ass to say the least! I have not been out with any other stock xp's yet but when I do I will def. take some pulls side by side to show the difference when we do...

I was also thinking maybe, I would like to come down and ride in your neck of the woods? Shoot some footage! Check out RK-TeK maybe talk to the owner...see what Rk Tek has planed for the future! Let me know if you are interested?

Thanks again, I am a firm believer in your kits and I will talk them up every where we ride!




First off all i can't belive how well this kit performs! Outrun all the sleds iv'e tested against, including a nytro xtx with challenger 136- 2" track up a steep mountain in almost 2feet  powder. He started up first, and i started in the back, and halfway up  i outrun him with the skis 1feet of the snow! All in my riding group was amazed of my shortie after the rk tek kit install. I got 120-1.75 inch ripsaw track and i have a thought time holding the skis down in a steep hill. lowered the front and lifted in the back


Rino Andersen Norway.


I have your cheater head and pistons along with your clutch and carb tuning specs in my Ski Doo Mxz 800 and have never been so happy with a performance upgrade! (you guys made me top dog in my group of mutts)
Hoping we can transfer that technology to watercraft racing.

Thank you,
Ryan Frokjer



My name is Mark P***** and I own a small engine repair shop(Sun Sport Sled&Marine) in Fort Saskatchewan, Alberta ,Canada.I personally own a XP with an 800 drop in kit and mpem re-curve and love it and would like to offer this kit and 860BB kit...ect to my customers. 



  Sled is still running strong this year with no problems at all. Have ran with some stock m1000,s that have told me that they have never been beat by a Doo. In 8 inches of snow on lake could pull up beside either one and slow down and then pull away. They even said they were very surprised that the sled worked that good.

  On the hill could give them a head start and pass them before the top of hill .(Long hill) Some of this could have to do with a 174 track as the GPS speed on the hill is quite a-bit more . Have ran with my buddies 2009 m800 with y pipe, pipe and intake that was the famous dyno 164hp and it isn’t even close.

 I don’t know what was wrong last year ,if the bore size was a-little bigger, jetting to lean or a little of both. With the cylinders redone due to nikasil coming off the sled has never ran this good as the pistons seemed to fit tighter after the redo.

  Jetting is 480’s needle (2007) in middle position, pods, Boyesen reeds, Dyno-port y and pipe. Could go down some more but wash is about ˝ inch and runs good so leaving well enough alone. Running 20% 110 to be on the safe side.  (3000ft to 7000ft )

   Anyways just wanting you to know this as I am sure that you get a lot of bitching at times. Keep up the good work and is it worth it to send you my cylinders and have the porting updated this summer as will be putting in new pistons anyways. Don’t think it needs it but it is cheap insurance.

  Drop me a line and let me know about the porting .

 Grande Prairie Alberta Canada   



I have been riding my sled alot this winter and it works great!!!
I have been doing really good in competition and even better on the mountains. I have raced alot off Yamaha turbos on pump gas and it have turned out great to my favor.

Now I am thinking on running race gas in competition.
Do you have some experience with race gas on M1000? and do you can make me some heads that will work with race gas?
Maybe I also need to change my timing?

Bjorn Terje Viki


Kelsey, I installed and ran your kit this weekend on my 09 M8 162 with an slp single and can.  For the 1st time since I've owned this sled I was finally able to hold RPM's when either doing short climbs or longer ones.  The only difference was on the short climbs my RPM stayed at 8050 while on much longer pulls it seemed to settle at 7940.  This kit was worth every penny!!!!!!  The two guys I ride with liked what they saw and I ended up letting them try my clutch, one of my buddies went and ordered one from Rob Kerch and the other guy is about to pry open his wallet too.  Now I have a couple fine tuning questions.  I started with your recommended settings of 68g primary cat light tip weights with the yellow white primary spring.  I also set the secondary spring tension on the second to the weakest setting.  My riding elevation is between 5 and 8k.  My goal was to reach or hold closer to 8100 on the longer pulls



Just spent 4 days riding and 4 of the guys I ride most with all asked what I had done because the sled worked noticeably better. Two of them asked if I had big bored it.

I did a few other things as well but obviously the drop in kit made a difference.

Just thought I would pass along a little positive feedback.

Thanks for a decent product.






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