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Discussion Starter · #1 ·
It seems like a lot of people on this forum don’t blink at dropping $1k+ for an aftermarket exhaust system, but that’s a little past reasonable for my budget. Anyway, I’d be walking with a limp if my wife found out I spent that much. Gotta be others out there in the same situation, right?

So when I decided I’d like a little more sound out of my ST4s, I did a little research on what it would take to open up the stock mufflers a little. I found some information on line and I also talked with one of the mechanics at the local Ducati dealer and came up with a solution that I’m extremely happy with. Here are step by step instructions and a few pictures.

Required tools:
Drill with 3/16” bit
Rubber mallet
2” masking tape
Cut-off wheel
Sawzall with metal blade
Pop rivet tool with 3/16”x 1/4” aluminum rivets



The obvious first step is to remove the mufflers from the bike. You can figure that part out on your own. If you can’t, stop now! It’s also a good idea to cover your work surface with towels or something soft to reduce the chances of scratching something you want to keep.



Once you’ve got ‘em off, make a mark on the aluminum sleeve next to each rivet location on the rear cap. This is important. Otherwise you’ll have a hard time getting the cap oriented correctly when you reassemble (don’t ask how I know).





Remove the two bolts holding on the mounting bracket. Next, you’ll need to drill out the three 3/16” pop rivets that hold the rear cap on. With these out, the rear cap should pull out easily. If it doesn’t, a light tap with a rubber mallet should move it.



Now, the aluminum sleeve should slide off. This might be tight. One of mine came right off, but the other needed a little coaxing. I held the sleeve with one hand and beat the muffler out with a hammer. Don’t worry about bending the outlet. You won’t be keeping it. But be careful not to ding the sleeve.



Once the sleeve is off, wrap 2” masking tape around the muffler right behind the mounting bracket holes. This will be your cutting guide.



Now take a cut off wheel and cut as deep as you can all the way around the perimeter. I couldn’t get all the way through with the cut off wheel, so I had to finish the job with a sawzall.



Surgery is done. It looks like you’ve removed a lot, but each of the pieces of muffler you’ve cut off only weigh about 1.7 lbs.



Time to close her up. Reinsert the rear cap back into the sleeve, lining up the rivet hole with the marks you made on the sleeve. Measure, mark, center punch and drill three holes around the perimeter of the sleeve, through the sleeve and cap, at about 1/4” from the back of the sleeve. I centered the new holes between the existing cap holes, but you can put them where ever suits you. Pop rivet the cap to the sleeve, and then put rivets in the existing cap holes.



Now slide the sleeve and cap back on the remaining portion of the muffler and bolt the mounting bracket back on. Ready to install and enjoy. The whole process doesn’t take much more than half an hour per side.

I’ve modified several exhaust systems on various bikes in the past, but have never had as good of results as this. The new sound is deep booming tone and moderately loud (too damn loud if you ask my wife), with no funny flatulent noises, like I’ve run into with past experiments.

I understand that with exhaust mods like this, you usually gain a little top end horsepower at the expense of low end torque, but my seat of the pants dyno can’t detect a difference. It would be a good idea to have the ECU adjusted, but I haven’t gotten around to that yet. I’m due for belts and valve adjustment in the near future, so I’ll take care of it all at once.
 

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great fix

Your info was perfect! I just got a st4 a week ago (my 1st Ducati) thought it sounded too quiet I got outbid on used ducati performance exhuast went for over 600 bucks Im getting my cutoff saw out tonight Thank you so much You saved many dollars
 

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I yam what I yam
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Great write-up and photos!

Just to clarify (yeah, I'm blond) the aluminum sleeve now encloses only the lower 1/2 of the muffler with the end cap riveted to the sleeve, correct?

Are you concerned at all about the durability of the aluminum sleeve exposed directly to exhaust pressure/pulses?
 

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I did this to my old SS, but back then (2001ish) there was a company that sold perforated stainless steel tubing. It could be had in 1.5" and 2" diameters. I do not remember the name of the company, but I do remember they are no longer around... I'm sure you could still source it somewhere; it’s just perforated flat stock rolled and spot welded. The nice thing was this company sold it catering to Ducati owners who wanted to core their exhausts, so the length was correct and they included a neat little end cap that gave you something to attach the new baffle to on the output side. The kit aloud you to remove the entire stock baffle assembly. With a little spot welding, and some fiberglass packing, you ended up with basically the same exhaust system you can buy in the aftermarket but with a stock look and the ever important EPA stamp still in place. It sounded tremendous and was much lighter after the fix. I used them for a while, but eventually fell to the Carbon Fiber sickness and found a set of Arrows for that bike.

The only thing I think I'd be concerned about in this day and age is not having a stock system to fall back on if the noise police finally get their way and actually enforce loud pipe bans everywhere. It's happening all over the country but it’s still isolated to small areas. This month's AMA magazine has an article on a new, easily completed, field test becoming available. BTW, the AMA’s stance on this is fair enforcement (cars and trucks too), not preventing the outright ban on loud pipes. They mention that they have not been an advocate of the loud pipe thing at all, only fair enforcement by not targeting just motorcycles. Just food for thought, my DP carbons aren’t going anywhere, but I did source a set of stockers just in case...
 

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It seems like a lot of people on this forum don’t blink at dropping $1k+ for an aftermarket exhaust system, but that’s a little past reasonable for my budget.
That's why my ST2 has new FBF/Forza slip-ons that I bought from a Ducati dealer that was going out of business. I only paid $305 shipped to the door for them......My wife's ST2 has a set of slightly used D&D slip-ons that I only paid $250 shipped.
 

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Discussion Starter · #7 ·
Just to clarify (yeah, I'm blond) the aluminum sleeve now encloses only the lower 1/2 of the muffler with the end cap riveted to the sleeve, correct?

Are you concerned at all about the durability of the aluminum sleeve exposed directly to exhaust pressure/pulses?
Correct, the aluminum sleeve encloses roughly the front 2/3 of the muffler with the cap riveted directly to the sleeve. I'm not too concerned about pressure. The opening in the cap is pretty big, so I don't expect problems.

I'm more concerned about heat. I'm not certain, but I suspect the sleeve will get hotter than it did before and this could affect the finish. But, I've put about 500 miles on it since the mod and no issues so far.

On a related note, I pulled my plugs last night to see if I'm running lean with the open exhaust. They look just like they did pre-mod. As I mentioned before, I can't detect a difference in the way the bike runs. It just sounds tons better now. I can't get the grin off my face :D!
 

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I've been thinking about "modifying" my pipes by enlarging the outlet hole to match that of the end cap.

When you look into the upper 1/3 portion you didn't use, can you tell if all or any of those internal baffle tubes are welded to the outlet wall? Does it look like you could use a hole saw, or would the cutout piece remain attached to the tube(s) inside?
 

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Discussion Starter · #9 ·
I've been thinking about "modifying" my pipes by enlarging the outlet hole to match that of the end cap.

When you look into the upper 1/3 portion you didn't use, can you tell if all or any of those internal baffle tubes are welded to the outlet wall? Does it look like you could use a hole saw, or would the cutout piece remain attached to the tube(s) inside?
Actually, that was my intention when I started, but it won't be quite that simple. The main center pipe runs continuously through the two rear chambers (maybe more) and is welded to the partitions between chambers.

What might work is to cut a two inch slit about two inches back from the rear of the muffler so you can cut the center tube off with a sawzall. Then you could use a hole saw to cut the center pipe out of the rear cap.

Like I said, that was what I had intended to do originally, but I started too far forward on the muffler. I got into the second from the rear chamber instead of the rear and was forced to amputate the whole works. No regrets though. Sounds awesome.
 

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Mr Leakered
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The mod you are describing is detailed here:

http://www.ducatiwiki.net/index.php?title=Norm%27s_ST4_stock_pipe_endplate_cut-out

I did this with my stock cans. It was boomy round my typical cruising RPM, so I added a lot of steel wool to the three small tubes to isolate the second chamber. A set of Remus cans sound a lot better and are quieter without any DB killer.

As you think, all the visible tubes are welded to differnt plates insided the muffler. The first chamber dumps exhaust to the third using the two pictured, or three on my ST, smaller tubes. The other three tube return the exhaust to the second chamber then to the outlet in the large center tube. Kind of goofy, but a lot of OEM mufflers use this or similar method to lengthen the run. Turning exhuast air 180deg twice over sharp-ended tubes is very in-efficient. This in-efficiency takes a lot of energy (noise) out of the exhaust.

I did feel some throttle response improvement and a bit more meat in the mid-range RPMs when I cored mine.

Have a good one.
 

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Discussion Starter · #11 ·
Hmm. This may be a little louder than I thought. I set off a car alarm yesterday while at an idle. :D Maybe the alarm was set a little to sensitive, but that never happened with the cruiser I used to have (Road Star Warrior w/ Vance & Hines Bigshots, no baffles). Still love the sound though.
 

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Mr Leakered
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I set off an aftermarket alarm in a parking garage. It happens. LOL.

One thing, start the Duc and go around back about 6ft behind and bend down to the level of your outlets. It is an entirely different sound since you are along the line of the boom.

I have yet to hear my own bike at speed. I'd like to know just how obnoxious, or not, I am. I suspect that I am somewhere just between, depending on time of day and position of my right hand.

Have a good one.
 

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wake my neighbors?

i was just about to get the grinder out and tear into this mod until i read the last two replies......

So am i going to wake my neighbors as i leave the driveway at 6:30 am on my way to work? I am not sure i want that headache.
 

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The pipes are louder with some of the mods you can do. They are still not as loud as my buddies Triumph or any given Harley. Or do what I did, move to the county! :D
 

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Solving problems...

Twerth - in your original post, you mentioned a problem with spending money on your motorcycle vis-a-vis The Wife. I got rid of The Wife...solved THAT problem - along with many others. :p

Thanks for the great how-to post.

I'd love to have a set of pipes like the old Norton Dunstall megaphones with the little reverse cone tip. That would look SO much better than the "tin can" pipes we now have. Hope some entrepreneur out there is paying attention.
 

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have a look at the emgo megs. jc whitney and d kirk have them. you just need to fab the connector pipes and add some stainless steel wool to take the edge off the sound. i put the shorty version on a dr650, it worked out well. i think they also have what they call "dunstall" version. here is a link to a pic of the dr meg equiped.
http://www.ducati.ms/forums/showthread.php?t=66868&highlight=megaphone
 

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Discussion Starter · #17 ·
i was just about to get the grinder out and tear into this mod until i read the last two replies......

So am i going to wake my neighbors as i leave the driveway at 6:30 am on my way to work? I am not sure i want that headache.
As far as the car alarm goes, I think when I backed out of the parking space, my pipes were probably within a few feet of the car and aimed straight at the grill. Otherwise, there might not have been a problem.

The Duc's not as loud as my Warrior was, and I left for work on that bike at 6:45am for four years with no complaints. Naturally, I take it easy until I'm out of the neighborhood. That said, people have to be able to hear it inside their houses. If someone was looking for something to complain about, that might do it. You'll have to gauge your relationship with your neighbors to decide if it's worth making the change.
 

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Mr Leakered
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i was just about to get the grinder out and tear into this mod until i read the last two replies......

So am i going to wake my neighbors as i leave the driveway at 6:30 am on my way to work? I am not sure i want that headache.
Seriously, anything you do to the mufflers is nothing compared to the steel clutche rattle in the ST2 and ST4. Prior to messing with the exhaust and without the quiet clutch, I could not have a conversation with anyone if my bike was idling with the OEM cover in place. With the quiet clutch, open cover, and cored/aftermarket cans, I can easily talk with someone inside my garage with the bike idling. I will contend that exhaust noise is a much more pleasing note than clutch rattle. Alloy clutch rattle is much better, but still. . .

After that, it is all in how you leave the 'hood. I'm at work by 6a to 6.30a. Since I've started modding my ST, four bikes have shown up in our small neighborhood, most with aftermarket pipes. A couple were already there, and one more is one the way once the economy improves. Crazy.

Have a good one.
 

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thanks guys....i may give it a try this weekend. It is supposed to rain so i should have lots of garage time:)
 

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I'd love to have a set of pipes like the old Norton Dunstall megaphones with the little reverse cone tip. That would look SO much better than the "tin can" pipes we now have. Hope some entrepreneur out there is paying attention.
Yes I love the Norton pipes too with the "whistle" note in with the rumble.

I've just gone through this mod exercise too with stock pipes. To be accurate, I picked up a set of Ducati 888 mufflers for $100 because I want to keep my stock pipes. I had an engineer make extension tubes to fit the ST4.

The engineer then got a long drill and bored out the centre tube so that gases ran freely straight through. Interestingly this made almost no difference to the sound. After scratching my head I decided this was because the outlet pipe is half the size of the inlet and most exhaust gases were still taking the long way round.

So......I then asked the engineer to cut two slots in the end of the muffler, on either side of the outlet pipe

OH BOY :D That worked. In fact I suspect it worked too well because peoples heads pop up on the street when I'm still 100 yards away.

In hindsight we should have bored two holes, tried it, maybe bored one more and job done. I haven't put the end-caps back yet so it may quieten slightly. Still, its an effective mod and I think drilling down the centre-pipe was unnecessary.
 
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