Modifying stock ST exhaust

[ShadyGrady]

Before I change to an aftermarket exhaust (Yoshimura) I would like to see if I can get a little more sound out of my stock system. I am not looking for any power gain - just a little more sound. It is easy to see the layout of the cat and muffler but no way to see the inside of the muffler. I removed the end cap and noticed that the exhaust exits through 2 small downturned pipes. I eased a flexible tube through the outlets and found that they flow out of even smaller holes in the rear of the muffler. My thought is to cut these 2 outlet pipes off flush with the rear of the muffler and then enlarge the two holes, then put the end cap back on.
Has anyone tried this or have any good reason that it won't work ( or that it will).
Thanks,
ShadyGrady
2013 Spyder ST

 

[coz]

nothing to lose

sounds like you have nothing to lose by doing a little surgery. i don't recall hearing of an st muffler being modified. got pics?

 

[Chupaca]

Have seen here..!!

where the tips were cut flush but don't remember how much sound changed. Getting the cat removed did make a change. Lamont can fix you up with that. Further than that have not seen any other mods...:thumbup:

 

[flamingobabe]

this sounds interesting....with the cat bypass you get a little more throaty sound......keep us posted

 

[ShadyGrady]

Thanks guys

Thanks guys. I am going to wait a few days to see if anyone has a concrete answer before I proceed. I really appreciate your input. Unless someone has a good reason not to proceed, I am going to give it a try and will document the process and the results.
Thanks,
ShadyGrady

 

[333Club]

waiting to see how this goes??

Before I change to an aftermarket exhaust (Yoshimura) I would like to see if I can get a little more sound out of my stock system. I am not looking for any power gain - just a little more sound. It is easy to see the layout of the cat and muffler but no way to see the inside of the muffler. I removed the end cap and noticed that the exhaust exits through 2 small downturned pipes. I eased a flexible tube through the outlets and found that they flow out of even smaller holes in the rear of the muffler. My thought is to cut these 2 outlet pipes off flush with the rear of the muffler and then enlarge the two holes, then put the end cap back on.
Has anyone tried this or have any good reason that it won't work ( or that it will).
Thanks,
ShadyGrady
2013 Spyder ST

Curious to see hw this turns out. Keep us posted please. Sound clip would be helpful

 

[coz]

have you started yet shady?

curious to see what you come up with.:thumbup:

 

[chief49]

Drilled Holes On Back Plate

I too removed the rear cover on the exhaust and drilled four 1/4 in holes into the back plate. There are actually two plates inside the muffler system and I drilled through both. Did not detect and changes in performance but certainly a difference in sound. ST in the shop now to get the cat removed and adding an HMF exhaust and JuiceBox controller. Hopefully they will be finished tomorrow and will post changes in performance and sound after a few miles.

 

[robtdonna]

Interesting, just removed the end cap myself today. Looking at end cap, thinking I can cut out the divider in the end cap and find a rectangular end exhaust tip to fit. Then as you said cut the 2 small pipes off and hog out the openings. Keep enlarging the openings until the desired sound level is achieved. Just a thought.

Before I change to an aftermarket exhaust (Yoshimura) I would like to see if I can get a little more sound out of my stock system. I am not looking for any power gain - just a little more sound. It is easy to see the layout of the cat and muffler but no way to see the inside of the muffler. I removed the end cap and noticed that the exhaust exits through 2 small downturned pipes. I eased a flexible tube through the outlets and found that they flow out of even smaller holes in the rear of the muffler. My thought is to cut these 2 outlet pipes off flush with the rear of the muffler and then enlarge the two holes, then put the end cap back on.
Has anyone tried this or have any good reason that it won't work ( or that it will).
Thanks,
ShadyGrady
2013 Spyder ST

 

[flamingobabe]

not sure if you guys know that atadude and Mr. Orange built a dual exhaust for the GS/RS...I was lucky enough to have atadude's dual exhaust on my RS....when I sold the RS I pulled it off and now my brother, lil'rabbit in the NW Washington has the dual exhaust on his 2010 RS......let me look up the threads...

here is ataDude's thread on mods...the exhaust stsrts on page 4...but read the whole thread...he is the master http://www.spyderlovers.com/forums/showthread.php?5753-Now-mine

here is Mr Orange's mods http://www.spyderlovers.com/forums/showthread.php?23263-The-modding-of-SpYder-1374

 

[ShadyGrady]

Thank you Flamingobabe and question for chief49

Thanks Flamingobabe - these 2 threads are fantastic. Really opens up the possibilities with a little imagination and a willingness to experiment.

Update on my progress. I removed the end cap and cut the two downpipes off flush with the back of the muffler. I found that there are inner pipes running to these 2 outlets and there is really no benefit to enlarging the holes in the muffler body any further. I replaced the end cap and find that the sound is a little deeper with some gurgling caused by the end cap. It is definetly an improvement, but not a big one.

Chief49: You mentioned that you drilled 4 x 1/4" holes in the back of the muffler. You said it changed the sound, but did not say what the change was. Louder? Deeper? Tinny? I am thinking of doing this as well but I wanted to know if you liked the sound it produced or not before I proceed.
Thanks,
ShadyGrady

 

[ShadyGrady]

Update

I removed my end cap again last night and drilled the 4 holes through both walls per chief49 - this is in addition to cutting the 2 down pipes off flush with the rear of the muffler. The sound is not a lot louder than stock but the tone is very deep. I am very pleased for the results given that there was no cost involved. I will probably still upgrade to a Yoshimura system later but I am not in any hurry.

If anyone else decides to give this a try, I will give you a few small pointers that I discovered the hard way. The rear of the muffler is very tough to drill through, so you will have to use drill bits manufactured specifically for metal. Even using metal bits I had to start with a very small drill bit and work up to the size I wanted. I tested the sound each time I increased the hole sizes. I ended up with 4 1/2" holes.

ShadyGrady

 

[SPYD3R]

THIS MAY HELP

THIS MAY HELP YOU....
an RT & ST mufflers are the same... inside and out...

if you cut along the existing welds, you end up with 3 pcs. the inners of the middle section will slide out... it's a 3 walled system: outter, fiberglass, and inner...
i have altered a number of these to the point of completely gutting everything inside, and glueing it back together, only to find the efforts were all for 'not' if the cat isn't removed...
BRP classifies the 'cat' as a 'pre-muffler', and that is exactly what it does; muffles 95% of the sound... why they even put a muffler on these things is beyond me...
if you need any more pix, i can post additional ones....
Dan P
Easley, SC
SPYD3R

 

[ShadyGrady]

THANKS!!!!

Dan,
Thank you for the pics! Now I see what I am up against. I have few questions for you:
1. I do not want to cut my muffler apart and weld it back together. Do you think I would see any additional benefit if I just took a large hole saw and opened up the rear end of the muffler but leave the bosses so I can reattach the end cap? Or am I probably getting as much sound out of it now as I would if I open up the rear with say a 4" hole saw?
2. How involved is removing the cat system? Is the O2 sensor in front of the cat or in the cat? When you remove the cat system how much fabrication do you have to do to mount a new muffler? How many other changes does removing the cat system entail?
Rather than taking the time to answer all of my questions can you just point me to a few threads that detail the process.
Once again, thanks. You are obviously very knowledgeable and I appreciate your advice.
ShadyGrady

 

[SPYD3R]

PM

Dan,
Thank you for the pics! Now I see what I am up against. I have few questions for you:
1. I do not want to cut my muffler apart and weld it back together. Do you think I would see any additional benefit if I just took a large hole saw and opened up the rear end of the muffler but leave the bosses so I can reattach the end cap? Or am I probably getting as much sound out of it now as I would if I open up the rear with say a 4" hole saw?
2. How involved is removing the cat system? Is the O2 sensor in front of the cat or in the cat? When you remove the cat system how much fabrication do you have to do to mount a new muffler? How many other changes does removing the cat system entail?
Rather than taking the time to answer all of my questions can you just point me to a few threads that detail the process.
Once again, thanks. You are obviously very knowledgeable and I appreciate your advice.
ShadyGrady

Grady;
PM me with a phone number, and we can talk about it...
Dan P
Easley, SC
SPYD3R

 

[ShadyGrady]

Done

Grady;
PM me with a phone number, and we can talk about it...
Dan P
Easley, SC
SPYD3R

Dan
Sent you a PM with my contact information.
Mike

 

[robtdonna]

Great thread and pics. I do believe Ill let things stay stock until I can change the whole shooting match !

 

[ShadyGrady]

Update and Thanks SPYD3R!!!!!

As you can see in earlier posts SPYD3R (Dan) offered to help me with my mission as he has modified numerous Spyder mufflers. Dan sent me a RS muffler that he had cut apart, gutted with the exception of 1 baffle, and shortened by 6". He would not let me pay for anything other than the UPS shipping charges. It is not a lot louder (I still have my cat system ) but the tone is deeper and it really looks great. I will post photos this afternoon. I am also going to change the heat guards to red - Dan had a few of these that he powder coated as well. It is not as loud as I originally intended but it looks and sounds so good I am more than happy. Mission accomplished.

THANK YOU DAN !

ShadyGrady (Mike)

 

[SPYD3R]

As you can see in earlier posts SPYD3R (Dan) offered to help me with my mission as he has modified numerous Spyder mufflers. Dan sent me a RS muffler that he had cut apart, gutted with the exception of 1 baffle, and shortened by 6". He would not let me pay for anything other than the UPS shipping charges. It is not a lot louder (I still have my cat system ) but the tone is deeper and it really looks great. I will post photos this afternoon. I am also going to change the heat guards to red - Dan had a few of these that he powder coated as well. It is not as loud as I originally intended but it looks and sounds so good I am more than happy. Mission accomplished.

THANK YOU DAN !

ShadyGrady (Mike)

i'm happy you're happy Mike....
when you remove the CAT, this kitty will purrrrrrrrr.....
Dan P

 

[ShadyGrady]

Heat Shields

Dan powder coated a set of heat shields in Lipstick red to fit the stock muffler he gutted and shortened for me. Love 'em or hate 'em - you have to admit that they they give the ST a little swagger.