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Magnaflow Under Tunnel Exhaust Install

Colorado Nytro

Extreme
Joined
Oct 31, 2008
Messages
71
Location
Westminster, Co
Country
USA
Snowmobile
Yamaha Nytro 09
I have had under the tunnel exhaust for about three years on an 08' and 09 MTX Nytro's. The muffler I first used was the glass pack cherry bomb style with a baffle insert. This ended up passing Colorado's noise limits but not to my comfort level as it got older. This is an easy mod for those who want more storage on the top side of the rear tunnel and for under the seat storage. I keep the items not used regularly under the seat, mainly emergency items, plus a few cups of oil in case the sled goes belly up for too long. I have not made any adjustments with air/fuel.

1. I cut my factory pipe about 1 1/2" from the front edge of the under the seat cut out. This is where the pipe starts to straighten out. I did this so that the muffler would lay as close to the top of the tunnel.

2. This is the Magnaflow muffler 11123 (ordered from Amazon; with Prime free shipping $84.00). I took the tail pipe off the old exhaust.

3. Fit the muffler to the head pipe and connect a muffler bracket to the front and rear. You can catch some frame material on both ends for supports. It works great. The under view shows the rear bracket.

4. The shot with the old pipe (glass pack) and the new Magnaflow. As you can see I reused the tail section. The tail is held to the muffler with a few sheet metal self tappers.

5. The block off plate is sheet tin now 3 years and running. Held in place with 1/4" self tappers. I put some aluminim foil tape towards the front to seal in where the bracket bolts pop up. Try putting a curve to the tin so you have some air gap between the muffler and the tin.

6. The insulation pillow is filled with normal insulation. I put my gear bag on top of this just in case things get too hot. The last bag did get cooked in one place, but not bad.

7. Completed view with the top tunnel bag mounted. It helps to have a mounted bag behind the gear under the seat to keep it secure.

Since this was a under the tunnel replacement it went fast like in an hour. First time around a few more than that. Hoping that Bamboo has lead me to the right muffler choice. Can not get the sled out of the trailer until Super Bowl weekend, will follow up with hopefully quieter ride results.

Sorry about the order of the pictures, this was my first post of "How To" on this site. For those needing any sound testing in the Co. area reach out to me I do free sound testing. I got certified with Co Parks and Rec's team and have exact same equipment: Sleds, Bikes, ATV's.
 

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It came out of the trailer today after all and was much quieter. The mountains will be the real test next week. I got the upper A-Arm bushings replaced today and did the shim's to the spindles to adjust the SRP or ski runner pressure. Next is the alignment. Can't wait to ride. How many others have this type of DIY exhaust?
 
I put the same magnaflow muffler on my sled 3 years ago but I mounted it in the stock location and installed a 3" stainless tip out the stock plastic looks AWESOME but sound even BETTER!!!!!!
 
Give you a little tip I learned when I did this to mine, when in deep snow the machine looses power big time due to the snow being forced into the muffler end I had to turn my exhaust end out a little and but like a shield on one side to allow the exhaust to escape when in deep snow..
 
Kirkgking will you please post a picture of what you did. We are getting 2' of the good stuff tonight. Just added the OFT steering relocator last evening. What a difference.
 
Yes it should my track is 2 inch lug and does not come close. Anyone else want to speak up on recommendations. ?
 
Please let us know how this exhaust works! I have been contemplating the same design for my xtx. I am considering mounting the muffler higher in the opening using a raised block off plate to get more track clearance. There was a thread about this setup and they had issues with clearance using a 1.75" BC track.
I am also considering using a dual outlet version of this muffler to help with snow clogging in deep powder.
 
Yeah I remember seeing that thread about this setup on the xtx. From what I remember the muffler has to be mounted about 3 inches from where the 3:1 collector is. I am going to give it a shot and see what I can figure out. I will be sure to take pics as I move along and hopefully it works out for me. I have everything on order so just waiting for it to be delivered. Might take me a bit to get it installed as I just added a baby boy to the family on the weekend but I will poke away at it and post a step by step when I'm done.
 
Slowey
Looking forward to that step by step on the install. I am going to wait until the spring to do mine. Dont want to interrupt a good season so far. Plus I still want to install some extrovert drive sprockets at the same time.

Good luck with the install!
 
Seeing as how I have a new born I can't get out in the next few weeks anyways so at least when the little guy is sleeping I can sneak out to the garage and turn a wrench. Otherwise I would wait till spring as well. Just waiting for my muffler to come in and then I will start the process.
 
This muffler works great!! Now I would like to know how I can limit the amount of snow build up under the tunnel. It must be an extra 50 plus pounds of weight.
 
Hey Colorado. Can u send me some pics of your setup? Where did you cut your header? Can I also take a measurement from the back of the tunnel to the muffler for me as we'll. thanks
 
The header is cut 1 1/2" just forward of the cut out for the tunnel (closest to the tank). That is the section of the pipe which gets straight; give or take. See tape measure picture in this thread. From my mud flap to the back of the muffler is 29 1/2". I have a short exit pipe attached another few more inches. My next challenge is to figure out how to reduce or stop under the tunnel snow build up. Who can help??
 
What if we ran an extension tube and had the exhaust exit the side of the tunnel right by the snowflap on a 45* downward angle? That would eliminate the moist exhaust air building up in the tunnle
 


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