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Discussion Starter · #1 ·
This mod is for those of you who want to keep the look of the stock exhaust, but just wish it was a bit louder than it comes stock. Should NOT require any additional tuning, but I will find out for sure later. Proceed at your own risk :)

I did this today using no tools other than a hacksaw and a vise (Okay, and a welder), just to show you that it can be done. Obviously, power tools make it go much faster, but it was nice to just have some time alone in the garage, so I decided to work harder not smarter :cool:



You will start out with a section of 2" OD stainless tubing, 6 inches is more than long enough. I used 16 gauge, if I did it again I would probably use 18 gauge just because it's that much easier to form and cut. The stock exhaust tip is 1.5" OD. This 2" tubing will fit, BUT you need to squish it in a vise and give it an oval shape. I squished it back about 2.5" from the end, just to make fitting easier.


Once you have your new tip formed, you are going to remove the 3 bolts holding the stock cover on. Cut the nut and bracket off of the exhaust tip (You'll be re-using this later), and now cut the tip off. You're going to cut right behind the second weld. You've now essentially removed the stock DB killer.

Now the fun part, you will reattach the exhaust cover with the two remaining bolts, and fit the new 2" tip. You'll need to cut the tubing at an angle in the back, or else it won't line up with the hole in the cover. I was lucky and got it on the first try, but 6" of tubing gives you plenty of room for trial and error. Once you think you have it, you'll tack weld the tip in place, and be sure to check the fit before you weld it! The fit is quite tight, so I advise to put plenty of tacks on, just to ensure it doesn't tweak on you. Once that's done, check fit one last time and have at it. I recommend using 309 filler, because your tip and the muffler are different alloys. 308 should be fine too though... But don't judge the crappy weld. Lol :rolleyes:

Now that your new tip is welded on, simply use the cover as a guide and mark your final cut line with a sharpie (You'll have about an inch of extra material). I chose to have mine protrude slightly past the cover... It's your call. Last step, is trimming the bracket slightly and rewelding the nut onto your new tip, so that you can use all 3 mounting bolts again. I'm not sure if this is necessary, but I decided to do it anyway.

And now you're done. It looks so close to stock, most people won't even notice. I just need to spend a few minutes sanding it down smoother
 

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Could you make a video? I want to hear it!
 

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Discussion Starter · #5 ·
Did you change your mind on cat removal
Not quite sure what you mean Dan? I'm leaving the catalytic converter in place though. I hacked into a stock muffler Marthy was kind enough to send me, and simply put without a plasma cutter it would just be WAY too much work to completely gut the muffler. This mod is just a compromise for a little bit more volume.

That said, I have a huge box o' bends sitting in the garage, and I'm going to play around with a couple header designs in the meantime :)

I'll try to get a video sometime... But I don't have a way of doing that right now, sorry guys. Hopefully soon though.
 

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From what I understood the whole thing was to improve the performance and still passing emissions for our Cali members. A tons of member on the FZ6R forum did that mod (not as nicely done...) and claimed a little gain in performance and better sound.

The most important th I ng is to look completely stock with betyer performance.

Sent from my SAMSUNG-SGH-I337 using Tapatalk
 

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Discussion Starter · #8 ·
Yep, Marthy has it right. I just did this as a way of contributing to the forum & showing how it's done, especially for the Cali guys who need to keep the stock exhaust system to keep the emissions guy happy. I'm going to try it out, but not sure yet if this is the exhaust I'm going to keep on my own bike... Time will tell.

Just for fun, a "side by side" with how it looks completely stock... I think you would have to be very familiar with this bike to spot the difference, and that was what I was going for. It'd match even better if I trimmed back about 1/4"... But I like how it looks this way.

Auto part Automotive exhaust Engine Vehicle Exhaust system Automotive exhaust Exhaust manifold Muffler Auto part Exhaust system
 

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Nice! Great idea for the niner.
I did something like this on my fz6r and loved the result.
This would improve the distinctive exhaust tone without being so loud.
 

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Discussion Starter · #10 ·
Thanks :)

I took the time today to actually install & test it out... Not going to lie, I'm really happy with it so far. Has the same tone / note as stock, it's just a bit louder. Not obnoxiously loud though... In my opinion, it's just right.

Maybe I will brave the 20* temperatures and go for a ride this week, if I can summon the courage to make it past the sheet of ice covering my driveway! :rolleyes:

And here are a couple of installed pictures.

Vehicle Tire Auto part Automotive tire Automotive exhaust Land vehicle Vehicle Motorcycle Automotive tire Car
 

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So took my little Exhaust cover off today, looks like the internal size of the muffler pipe is the same until just before the weld for the tip . Thinking I can get away with cutting it on the outside weld to retain the stock exhaust cover mount. Tell me if I am wrong but I see no advantage to cutting it off at the second weld......
 

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Discussion Starter · #12 ·
Yeah, you would be right Nick if all you're doing is cutting the tip / DB killer off. I cut farther back because I needed more than a couple inches to form the new tip I welded on... If that makes sense. I don't usually try to weld ovals to circles :) If you're just going to leave the cut edge and not weld a new tip on, then what you're saying should work.
 

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Nice, I love the look of the stock system. I just want a bit more sound, especially from idle up to around 4,000 rpm.

Thanks for the pics, and write up, hope to see a vid soon.

Is it noticeably louder at idle, and low revs?
 

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Discussion Starter · #14 ·
I will honestly try to get a video up, but it's going to have to wait a bit. It seriously sounds just like stock, but louder... So I'm going to need someone with a stock exhaust in the video too, for comparison. Otherwise the video might be almost worthless lol.

Idle is definitely louder than stock, I'd need to compare with another bike to say how much different it is with some RPM... I went about 3 weeks without riding when I did the mod, so my "memory" of how loud it was previously wasn't fresh. I'd say low RPM was still somewhat louder, but can't honestly say how much :confused: It got less noticeable as the RPMs climbed up.
 

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I will honestly try to get a video up, but it's going to have to wait a bit. It seriously sounds just like stock, but louder... So I'm going to need someone with a stock exhaust in the video too, for comparison. Otherwise the video might be almost worthless lol.

Idle is definitely louder than stock, I'd need to compare with another bike to say how much different it is with some RPM... I went about 3 weeks without riding when I did the mod, so my "memory" of how loud it was previously wasn't fresh. I'd say low RPM was still somewhat louder, but can't honestly say how much :confused: It got less noticeable as the RPMs climbed up.
Yes, you would kind of need a stocker alongside to compare to. Good to know it's louder at idle, fine by me if it's not much different (or the same as) from stock at high rpm's.
 

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So took my little Exhaust cover off today, looks like the internal size of the muffler pipe is the same until just before the weld for the tip . Thinking I can get away with cutting it on the outside weld to retain the stock exhaust cover mount. Tell me if I am wrong but I see no advantage to cutting it off at the second weld......
Unfortunately this doesn't work (and there would be no advantage cutting it off at the second weld). I cut mine off today. I cut the tip off right after the weld that is closest to the tip, right before the nut with the tangs that hold the cover on. That's where the outside diameter is as large as it gets on the tip of the outlet. The O.D. at that point is about 45.3 mm, almost 8mm (over 1/4 inch) larger than at the tip. That larger O.D. doesn't translate to the inside diameter however. I thought the pipe was tapered I.D., but it's not. It's double walled, so the I.D. is the same all the way from the tip, to inside the muffler body. So the I.D. is around 35.56mm from inside the muffler to the tip. So this " removing the stock D.B. killer" the original poster talks about isn't there, it only looks like it from the O.D. of the tip.

I wish the original poster would have shown pics of the pipe he cut off, and the remaining part of the pipe/muffler. I have pics on my laptop that I will post, if I can find where they went to. I wonder if the O.P even measured the pipe in different places to see if there was a diff in diameter. The only way to see an increase in I.D. would be to cut away some of the second wall of tubing coming from inside the muffler itself, or if you cut back further than the second weld (behind the nut and tangs that hold the cover on). That is where the pipe starts to round out (kind of bell shaped) and is welded directly to the muffler. Kind of hard to explain, if you look at the O.P.'s pics you might get the idea.

At any rate, not trying to slam anybody, or their mod, but the I.D. of the pipe where I cut mine, and where the O.P. cut his, doesn't change (unless our pipes are different internally) from stock. Although the O.P. never actually said it did. I just assumed the diameter changed because he mentioned "removing the stock D.B. killer". He did say his mod made the bike louder than stock, and that may well be. My ECU is on it's way to nick currently, so I don't know if what I did changes anything.
 

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Discussion Starter · #17 ·
Okay Verseys, I'll try to show how it works.

Here's a very crude 2-dimensional diagram of how the stock muffler is laid out. Exhaust enters the muffler towards the front, and first hits the catalytic converter. From there, it flows into all sorts of baffling (It's all marked by the crosshatch pattern, because I honestly don't know exactly how the baffling & cat is laid out). There are actually three exits from the "baffling chamber"... I believe all are the same 1.5" size. One of them flows straight through, and becomes the exhaust tip. But two others protrude about an inch past the "baffling chamber", and simply dump there into an open chamber.

Now you see on the picture of the cut off piece, there is actually a hole cut that opens the main exhaust tip up to some sound waves just bouncing around. Cut it all the way open, and you essentially allow sound waves from all three tubes to exit the tip, instead of just bouncing around in there. Clear as mud?? Sorry if it isn't, I'm trying lol.
 

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Okay Verseys, I'll try to show how it works.

Here's a very crude 2-dimensional diagram of how the stock muffler is laid out. Exhaust enters the muffler towards the front, and first hits the catalytic converter. From there, it flows into all sorts of baffling (It's all marked by the crosshatch pattern, because I honestly don't know exactly how the baffling & cat is laid out). There are actually three exits from the "baffling chamber"... I believe all are the same 1.5" size. One of them flows straight through, and becomes the exhaust tip. But two others protrude about an inch past the "baffling chamber", and simply dump there into an open chamber.

Now you see on the picture of the cut off piece, there is actually a hole cut that opens the main exhaust tip up to some sound waves just bouncing around. Cut it all the way open, and you essentially allow sound waves from all three tubes to exit the tip, instead of just bouncing around in there. Clear as mud?? Sorry if it isn't, I'm trying lol.
Thanks for the diagram of the guts, interesting. I sure don't remember seeing or feeling the little round hole cut out that is shown in your pic. I'll have to look again. At any rate, with the hole cut out, and the separation between the double walled pipe, there must be a little extra exhaust gas escaping, and creating a little more noise. I'll be anxious to find out, when my ECU gets back.
 

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Interesting reading. Thanks for both the post of different attempts.
I'm finally going to put some decent k's on my bike next month. Depending on how it treats me on the california trip.
If the stock exhaust is indeed lame, I will attempt this change.
 

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Discussion Starter · #20 ·
Thanks for the diagram of the guts, interesting. I sure don't remember seeing or feeling the little round hole cut out that is shown in your pic. I'll have to look again. At any rate, with the hole cut out, and the separation between the double walled pipe, there must be a little extra exhaust gas escaping, and creating a little more noise. I'll be anxious to find out, when my ECU gets back.
Post up your results & opinion once you get your ECU back, if you would. I gave mine a good run, but being only 30 degrees out didn't push it too hard... Didn't feel like it affected the tune at all though. I'm curious what your impression is, and what you think of the volume level too.
 
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