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Needed: Mistral db killer for Griso

W

wittangamo

Cruisin' Guzzisti
Joined
Sep 30, 2011
Messages
166
Location
Richmond, VA
I got a Mistral conical carbon fiber muffler for my Griso on eBay for what seemed like a bargain price. When it arrived, it was missing a db killer. My bad for not asking before bidding, and the seller says he never had one.

I know Mistral makes a "racing"version without and an "approved" version with. I also know that the db killer is available as a separate part. What I don't know is whether I have the racing version and/or whether a db killer would fit if I ordered it. I sent an e-mail to the factory in Italy, but no answer yet.

I've seen photos that show two different types of attachment, a bolt and a clip. I don't see a hole for a bolt.

8517576607_fb2529dc0a_z.jpg


I haven't installed it yet, and would like to figure out what my options are beforehand.

I could put it back on eBay, and even with full disclosure I'm pretty sure I could get what I paid for it.

The only place I can find Mistral db killers listed online is Stein-Dinse in Germany, though it's hard to tell from their catalog which model I need. Not that expensive at about $40 before shipping, but I'd hate to make a mistake in an overseas order and dig my hole any deeper.

Can anyone here tell from looking at the photo if a db killer would fit this muffler? Anybody have one they're not using and would like to sell?
 
GuzziMoto said:
http://www.dirtwerkz.com/Pages/products/exhaust/dB_Dawg.html
These people have been making them for years. They are not brand or pipe specific, just sized to fit in different sized pipes. The internal versions would likely work better as far as looks go.
Click to expand...

Looks interesting, but I don't see a "dB Dawg" big enough to plug the Griso can and they warn it might require fueling changes. I'm going to try and hold out for the Mistral version -- which is also cheaper. ;)

I just need to find one I know will fit.
 
Yes that pipe is designed to take a mistral db killer you could buy from mistral direct or through a dealer. The dB killer is just a round tube with a few holes drilled in it and i'ts restrictive some folkes drill more holes in it to go halfway. It just inserts and a securing bolt holds it in the bottom hole. I love the muscle car wail with it out. I think it's safer filtering in heavy traffic. Above 40 with a screen on a bike the wind noise is louder. I would try it as it is. I guarrantee you'll smile when you hear the sound of a proper engine.
 
I have an oval Mistral on my B11 and it came without a dB killer. To tell if your had one when originally sold, look for a tapped hole at the bottom of the output throat.

The noise level on mine is tolerable when driving around town, but gets loud when accelerating hard.

If yours doesn't have the bolt hole for the dB killer, an end cap with the dB killer might be available. You'll just need closed end rivets to reassemble.
 
The db Dawg people say they make them for up to 2 1/2" diameter outlets. Is yours bigger then that?
The stock db killer is just a restrictive tube in the end, nothing high tech. The db Dawg looks more interesting to me.
As for jetting changes, if you have ANY motor fueled for an open exhaust and you add a restrictor to reduce the sound levels you are going to reduce the flow and change the fuel requirements of the motor. In theory an FI motor with an O2 sensor SHOULD compensate for those changes. Will it? I have little faith in the MM FI system Guzzi's use. My Buell had a Fantastic FI system that adjusted and corrected quite well. You could actually feel it learn a change in flow. The Guzzi system not so much.
 
Rafael: Unfortunately, I don't see a tapped hole. I suspect this is the "racing" model, sold without a db killer.

GuzziMoto: Inside diameter is just under the max at 2 and 7/32". The biggest Dawg would probably fit, but like you I'm concerned about the fueling.

nel: I suspect you're right about the sound. The stock muffler is too quiet and I like the audio clips I've heard from the Mistral with and without the db killer.

But I'm getting conflicting advice on how it will run. Some say it will work just fine. Others say the Griso 8V needs back pressure to perform at its best with the stock ECU.

Can't afford a reflash at the moment, so it seems I have three choices.

1.) I can run the Mistral without the db killer and see if I can live with it.

2.) I can try to find a db killer that will fit and figure out a way to mount it.

3.) I can stick to the stocker, resell this Mistral and save up for a new muffler with db killer and/or cat-con.

I appreciate all the advice so far, but I'm still not sure which way to go.
 
wittangamo said:
Rafael: Unfortunately, I don't see a tapped hole. I suspect this is the "racing" model, sold without a db killer.

GuzziMoto: Inside diameter is just under the max at 2 and 7/32". The biggest Dawg would probably fit, but like you I'm concerned about the fueling.

nel: I suspect you're right about the sound. The stock muffler is too quiet and I like the audio clips I've heard from the Mistral with and without the db killer.

But I'm getting conflicting advice on how it will run. Some say it will work just fine. Others say the Griso 8V needs back pressure to perform at its best with the stock ECU.

Can't afford a reflash at the moment, so it seems I have three choices.

1.) I can run the Mistral without the db killer and see if I can live with it.

2.) I can try to find a db killer that will fit and figure out a way to mount it.

3.) I can stick to the stocker, resell this Mistral and save up for a new muffler with db killer and/or cat-con.

I appreciate all the advice so far, but I'm still not sure which way to go.
Click to expand...

A few comments.

You may need to add another choice or mod #1 to read something like this: "I can run the Mistral without the db killer and see if I and the public and LEO's can live with it.

I also have to say that I think the stock pipe sounds grand, especially rolling through 5 - 7 grand. :laugh:

It does look a bit ungainly, or, at least, it once did, tho I have gotten used to it. OTOH, I do now have Termi mounted and it does sing "loverly."

Good luck on a solution. I'm not you, but I'd lean toward door 3 unless the in-town sound is sustainable without too much of the wrong kind of attention. Admiring looks by folks 5 and up are the right kind of attention. ;)

Bill
 
wittangamo said:
GuzziMoto: Inside diameter is just under the max at 2 and 7/32". The biggest Dawg would probably fit, but like you I'm concerned about the fueling.
Click to expand...
While I think the fueling between with and without a db killer would be different I think the difference between the db Dawg and the Mistral db killer would be a wash. Anything you put in the pipe to reduce the sound is going to reduce the flow. I think the db Dawg is a more creative db killer design then the Mistral version, which is pretty much just a smaller diameter pipe to reduce the opening.

Pete Roper is someone who's opinion I respect, and he seems to be quite sure the 8 valve motor needs back pressure to run right.
Any db killer, whether from Mistral or the db Dawg people should achieve that.
 
Good advice from all.

Mike at MPH has offered me a good deal on a Mistral db killer.

I think I'll mount the muffler without it to see if I can live with the noise and performance, then try to install the db killer (it wants a 6 mm bolt hole my muffler doesn't have.)

If all goes well, I'll have a basis for comparison. If the experiment fails I'll sell the muffler to someone with more savvy and/or a flashed ecu.

Now all I need is some garage time and a little warm weather. B)
 
wittangamo said:
Good advice from all.

Mike at MPH has offered me a good deal on a Mistral db killer.

I think I'll mount the muffler without it to see if I can live with the noise and performance, then try to install the db killer (it wants a 6 mm bolt hole my muffler doesn't have.)
Click to expand...

Sorry to revive an old thread,,,
Were you able to mount the db killer in the Mistral pipe?

I just got mine(db killer). The pipe is the "race" version that was never drilled for an insert, so I am trying to figure out the easiest way to secure it. Drilling into stainless can be a pain and I don't know if I can get my drill in that far.

Thanks for any suggestions
hs
 
My Mistral was the same as yours, a "race" model with no set screw for a db killer. To complicate matters, the db killer I got for cheap had a bend in it -- obviously designed for a different model. Wouldn't go in at all.

A local machine shop cut it to remove the bend and re-welded it. The fit was so tight I had to bang it in with a block of wood and a hammer.

No way it's ever coming out, but there is a slight vibration ringing when I rock the throttle on a cold start. At idle or once warm, I don't notice it and it isn't an issue for me.
 
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