Inside the FJ muffler

[adjuster]

Still have not done it.
Need to get it done before April, when I can ride again.
 
I've decided to keep it simple.
 
Cut off the entire "bulb" area at the can housing.
Cut the inner "S" pipe from inside the tail pipe. Slip the "outer part" off, and this will leave the "S" pipe mostly intact, but only sticking out less than an inch or so.
 
Drill a series of 1/2" holes along the "X" formed into where the Cat exits. This should allow plenty of exhaust flow, and more sound, but since they are only 1/2" in diameter, not too much sound.
 
Leave the cat alone. It has just the right amount of back pressure for better low end power/Tq.
 
Fit the cover, and the "crushed slightly" for an Oval shape exhaust tip. I have some 4" ID pipe, and I think that will work great. The stock trim cover hopefully will just fit, and I will trim the "end cap" to fit as needed for a nice oval slash tip.
 
Tack weld it, check for final fit, and weld it all up closed. Then paint the entire exhaust with Techline "Turbo Black" ceramic coating, wrap the headers with Ti colored ceramic weave, not the fiberglass stuff, and then seal the wrap with more turbo black to keep it from taking up water. (and it holds the fibers together better over time too.)
 
Should be not too loud, flow great, and yet still have the stock low end power that most "full" exhausts lose in favor of better top end peak power. (That I don't use as much as the low end on this bike.)

[duhs10]

For those of you that have done this mod.... what kind of flash did you guys go with? Im going to do this mod in the next few weeks, as well as, send off my ECU to vcyclenut. Not sure to keep with the stock fuel map or have it flashed like a slip on.

[sheridan]

Does anybody have downloaded photos of the process? My English is not enough to understand without pictures

[papac2000]

Initially it was untuned. I now have a flashed ECU, but the mod works just fine with a stock tune.

[scott]

Hi All, Just curious if you guys think it would be possible to use a hole saw to create an opening between the exhaust pipe and the third chamber? Basically sticking a long 1.5" hole saw bit inside the exhaust should bite and drill through at the first bend in the pipe, this would eliminate the need to cut open an access panel and weld it back. I will be buying a '17 FZ-09 soon and really want to do this mod but have zero welding experience or equipment.
 
To me, it seems like this might work but wanted to run it by people that have much more experience in case it is a dumb idea and I will break things.
 
I can post a picture if I'm not making any sense. 

[scott]

After seeing how difficult it is to drill stainless steel pipe, I'm going to find a local welder with SS experience to do the full mod.  
 
Thanks again to everyone in this thread for an awesome mod.

[kdimitris]

Finally got out to do a test ride up in the canyons. I can now hear my bike as I go thru the gears !  
Triple sound is very addicting...  
 
Really glad I did this project, and it cost almost nothing. Just time. Here's the vid:
 
[video src=https://www.youtube.com/watch?v=uCBeU9R3FsY]
 
Ty

Hi there!! is there any possibility to upload pictures about what you've done  with your exhaust? My english is not good enough, so i didn't understand everything to make this mod to my bike too. 
 
Thanks in advance!!!

[duhs10]

Finally got out to do a test ride up in the canyons. I can now hear my bike as I go thru the gears !  
Triple sound is very addicting...  
 
Really glad I did this project, and it cost almost nothing. Just time. Here's the vid:
 
[video src=https://www.youtube.com/watch?v=uCBeU9R3FsY]
 
Ty

Hi there!! is there any possibility to upload pictures about what you've done  with your exhaust? My english is not enough good, so i didn't understand everything to make this mod to my bike too. 
 
Thanks in advance!!!

Unfortunately that forum member is no longer with us.. there are some other pictures within the thread that show the basic idea behind the mod.
 
The basic idea is cut the top of the muffler open, cut the S pipeout, drill a hole to the other chamber, but a bigger outlet on it if you want, and weld it back together.
 

[kdimitris]

I would like a clarification please.
1. Should i weld a small piece (from the S i'll cut maybe) of tube to the hole from the 3rd to the 2nd chamber?
2. Thinking to cut S pipeout only about 3 or 4cm, from the 2nd chamber side, so will remain a piece inside the 3rd chamber like in photo below.
https://s26.postimg.cc/ygf87ezpl/Full_Size_Render_copy.jpg' alt='Full_Size_Render_copy.jpg'>
 
 
 
What is your opinion?
Thanks in advance!!
 

[duhs10]

Modded the stock exhaust on my 2016 FJ-09 this weekend following the directions already provided so far in this excellent thread! Highlights: • Removed and re-installed without removing the center stand—key to this is to un-screw the radiator hoses (two screws, takes 2 mins) as pictured below. This frees up the manifold for easier maneuvering.
• Opened chamber and removed the “s-curve” pipe with a 4” cut-off tool
• Added extra hole from the cat chamber into the rear chamber with a 1 ½” hole saw
• Outlet pipe kept stock, ECU stock
• Got a friend to weld it back up
Very happy with the mod, it’s a much deeper tone and overall a little louder, but not too much to make it obnoxious. Feels like it removes some of the jerkiness a little too in A and STD modes. No pop on decel, but does give a nice rumble that wasn’t there before.
Time: 3-4 hours
Cost: If you have the tools and can weld, $0

 
@kdimitris yes. 1. Welding piece of the S Pipe is probably not necessary, but if you want to do it, then go for it. 2. yes leave a bit of the S Pipe sticking out of the 3rd chamber. There are 2 other pipes there that will you can kinda match it to.
 
I quoted a post from earlier in this thread that shows you what the end result inside the muffler should look like.
 

[kdimitris]

Modded the stock exhaust on my 2016 FJ-09 this weekend following the directions already provided so far in this excellent thread! Highlights: • Removed and re-installed without removing the center stand—key to this is to un-screw the radiator hoses (two screws, takes 2 mins) as pictured below. This frees up the manifold for easier maneuvering.
• Opened chamber and removed the “s-curve” pipe with a 4” cut-off tool
• Added extra hole from the cat chamber into the rear chamber with a 1 ½” hole saw
• Outlet pipe kept stock, ECU stock
• Got a friend to weld it back up
Very happy with the mod, it’s a much deeper tone and overall a little louder, but not too much to make it obnoxious. Feels like it removes some of the jerkiness a little too in A and STD modes. No pop on decel, but does give a nice rumble that wasn’t there before.
Time: 3-4 hours
Cost: If you have the tools and can weld, $0

@kdimitris yes. 1. Welding piece of the S Pipe is probably not necessary, but if you want to do it, then go for it. 2. yes leave a bit of the S Pipe sticking out of the 3rd chamber. There are 2 other pipes there that will you can kinda match it to. 
I quoted a post from earlier in this thread that shows you what the end result inside the muffler should look like.

 
duhs10 thanks!!!!

[kdimitris]

One more question to anyone who "knows about".
From factory, yamaha exhaust has a pipe from 2nd to 3rd chamber, right after cat. Is there really a need for an extra hole and if so, is that ok for back pressure?
In conclusion, i don' t wanna harm torque or hp of the bike.
Thanks in advance!!
 
P.S. Ready to do the mod!!!

[kdimitris]

One more question to anyone who "knows about". From factory, yamaha exhaust has a pipe from 2nd to 3rd chamber, right after cat. Is there really a need for an extra hole and if so, is that ok for back pressure?
In conclusion, i don' t wanna harm torque or hp of the bike.
Thanks in advance!!
 
P.S. Ready to do the mod!!!

 
No one???

[duhs10]

One more question to anyone who "knows about". From factory, yamaha exhaust has a pipe from 2nd to 3rd chamber, right after cat. Is there really a need for an extra hole and if so, is that ok for back pressure?
In conclusion, i don' t wanna harm torque or hp of the bike.
Thanks in advance!!
 
P.S. Ready to do the mod!!!

The original post of this thread did 2 versions of the mod. In the first version he cut the S Pipe only. It gave him 1hp increase and a little better sound.
 
The 2nd time he modified the exhaust he put the additional hole from 2nd to 3rd chamber and a slightly bigger outlet. He got a significant increase. 112whp and 68lb/ft of torque on the stock ecu settings.
 
So I would say that if you are going through the trouble of opening the muffler, you should put the additional hole between the chambers.
 

[kdimitris]

Then, i' ll do the mod V.2 !!!
Thanks a lot!!!