Coffman Shorty Exhaust - Now I’m Thumping!

Much louder, I would say borderline h____ f______ loud.

As far as tuning goes, a slip on or a k&n is pretty much max for stock.

After that get a Coober.
 
Thread revival for 2022!

I installed a Coffman Shorty Slip-On on my 2020 Svart 401 today. Took less than 10 minutes to install with no fitment issues. Came with a new clamp, but need to re-use the OEM muffler gasket by the clamp. I ordered it from Coffman's website specifying the polished tip and no manufacturer label ($250). Looks great this way to me!

The baffle for the Coffman is removed with a spring retainer pliers (had to buy one at Menard's for $5.99). The rest of the factory exhaust (resonator and cat) is still equipped. It is louder than stock, but not too obnoxious. Has a slightly deeper tone under load when going through the gears than when revving in neutral in my opinion.
If you also want to remove the resonator and/or cat, it might be better to keep the Coffman baffle in place so as not to be too loud, but that's based on other reviews that I've read and watched.

Sound clip in my driveway:
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Coffman 3.jpgCoffman 2.jpgCoffman1.jpg
 
BISavage said:
So as mentioned above, here is how it looks with the first option, this way the Insert stays in so its not completely opened:
View attachment 1899

The piece that is removable (and yes, I mangled it severely in the process...):
View attachment 1900
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Actually, I found the baffle can be removed easily without damaging it by using a snap ring (or retaining ring) pliers . I removed mine, but don't forsee putting it back in, unless I did more exhaust work and needed it to be quieter.

This shows the install, but removing it is basically the video in reverse.

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Dan00Hawk said:
Actually, I found the baffle can be removed easily without damaging it by using a snap ring (or retaining ring) pliers . I removed mine, but don't forsee putting it back in, unless I did more exhaust work and needed it to be quieter.

This shows the install, but removing it is basically the video in reverse.

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Click to expand...

That is Option 2.

Option 1. is described in the instructions, you need to remove the baffle, drill out the rivet holding the screen to the baffle, pull the screen off (its painted on so...), then reinstall the baffle minus screen.

This will give it a completely different sound compared to baffle with screen, and also compared with no baffle... so basically with the Coffman you have three different sounds to choose from.
 
BISavage said:
That is Option 2.

Option 1. is described in the instructions, you need to remove the baffle, drill out the rivet holding the screen to the baffle, pull the screen off (its painted on so...), then reinstall the baffle minus screen.

This will give it a completely different sound compared to baffle with screen, and also compared with no baffle... so basically with the Coffman you have three different sounds to choose from.

Excellent choice in Tip Color 😎
Click to expand...
Ahhh, so you're talking about the main "permanent" baffle, not just the removable "db killer baffle". Got it now. :)

Once I saw the polished tip option for the Coffman, that's what got me to buy it.
 
I mean this part:

Screenshot_20220406-231319_Samsung Internet.jpg


The purple arrow points almost directly at the rivet to remove, and the trapezoid shape highlights the piece that gets taken off.
 
My 2nd attempt at "Ahhh, I got it now..." :LOL: I didn't realize you removed the screen from the insert, but now with the photo I see what you mean. Pictures are worth 1000 words! ;)

How would you describe the sound difference with the "insert without the screen" vs having the insert removed entirely?
 
Ride by video of my Svart with just the Coffman pipe at the end of this short video (after the 24 second mark after a few other vehicles pass by). Bike at the beginning is a BMW S 1000 R with no cat and Akropovic, so a little deeper than my Husky.
🙂

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@BISavage do you have the competition works chamber delete? I can't tell from the posts. Thinking of the Coffman, but wondering about the chamber delete as well...I don't want it crazy loud...but just nice.

R
 
LOL. Also, @BISavage I noticed you liked the Arrow Pro Race too! Another one I was looking at.

hqvadventure.com

Arrow Dark / Pilen Svart

Seems to have taken the longest time to get my hands on one of these, and it was worth the wait; especially for everyone else it would seem. Installed the Arrow Pro Race "Dark" and have a few hundred miles on it so far. First impressions: smooth deep throaty mellow. I havent had it on any...
hqvadventure.com hqvadventure.com

Sooooo, which have you kept? haha. Which is the nicest sound (in your opinion...obv personal preference).


R
 
BISavage said:
Coffman's sells all it individually on their website.
Click to expand...
Yeah I just managed to recoup the db killer from the shorty pipe the Coffman replaces and fit it inside the end cap. I like the tone, its its own thing. I'll try it and If too subdued I'll cut it shorter for a bit more oomph..

IMG_0090.jpg
 
Lozion said:
Yeah I just managed to recoup the db killer from the shorty pipe the Coffman replaces and fit it inside the end cap. I like the tone, its its own thing. I'll try it and If too subdued I'll cut it shorter for a bit more oomph..

View attachment 5527
Click to expand...
Have you done this already? I am curious if this works. I have the Coffman exhaust and even with the DB killer it sounds obnoxiously loud like a dirt bike. If this mod of your works then that will help a lot
 
BISavage said:
Are you running without the Chamber?
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I am running with the full stock chamber and the DB killer. It sounds like a 4 stroke dirt bike. That to me makes the bike sound cheap compared to the baffled sound from the stock exhaust that came from this bike. Loud exhausts on slow bikes sound like your a poser. It reminds me of the kids with Honda groms that have very loud exhausts that can only go 60mph top speed.

I love the minimalistic look since the large stock exhaust is simply too much weight which is required to baffle the sound. This is just physics. I just don't like the sound output. Can't have it both ways. Therefore I deal with the sound and wear earplugs and have to also deal with the fact that I too am a poser on the road with a slow loud bike. Grrrr Sad

This is why I'm very interested to know if the added baffle in the catalytic converter will work and would love to hear the end result.
 
Ok well here is what I did. Ran the bike with this cheapo GP shorty pipe that is popular with Duke owners straight at the expansion chamber:

IMG_5484.jpeg IMG_0119.jpeg

Gave me the poser vibe sound so I bought this KTM RC390 Coffman exhaust on eBay. Its a bit longer then the Svart model so I had to fit a mounting bracket:

IMG_0403.jpeg

It's a bit loud empty (came without the db killer) so I took the db killer from the shorty and noticed there are 3x M10 screw holes on the Coffman's end cap (to allow it to tilt) so I inserted the db killer & screwed it in place:

IMG_0404.jpeg

I'll upload a vid of the sound which to me is the sweet spot..
 
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