Cat advice?
That's fine, I'll jump off the thread. No amount of common sense is going to fix some minds.
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,198
Likes: 3,028
From: St.Louis Mo.
i ahve taken head temps at the spark plugs on two bikes with the only differance being one had the cat the didn't. temps were 15 degrees differance. next time we are out i will take temps at header pipe and collector. if you run mufflers you won't get any popping unless you run very free flowing ones. popping is caused by reversion by letting in fresh air and 02 sensors read this as lean and adds more fuel creating the popping noise you are hearing. i do know one thing my bike is much more comforable to ride with the cat gone.
Elite HDF Member
Joined: Oct 2010
Posts: 3,504
Likes: 12
From: DOWN SOUTH
That wasnt meant to offend you Ultra, appoligies if it did. Its just seems like
As for your question, it has been said it causes cross talk because the cat is not there to keep exhaust from being sucked back in the open chamber, backpressure thing. Do a search on here and you will see. Sorry bout that.
As for your question, it has been said it causes cross talk because the cat is not there to keep exhaust from being sucked back in the open chamber, backpressure thing. Do a search on here and you will see. Sorry bout that.
Road Master
Joined: Oct 2009
Posts: 785
Likes: 2
From: SE TN
Before you do it, I suggest you ask yourself "Why?" I have been reading all the threads on this issue for years and have come to the conclusion that no one can show that it accomplishes anything meaningful and that it can, in fact, cause problems, including decal popping and backfires and can screw up how your ECM operates.
This is a LONG thread, but I suggest you read all of it. You will get both sides of the issue in detail. You can decide for yourself which side you think is more credible. https://www.hdforums.com/forum/touri...eal-facts.html
In another, more recent thread, I challenged the posters to provide real evidence that gutting the cat accomplishes anything and was met with deafening silence. (https://www.hdforums.com/forum/touri...t-removal.html ) All you ever hear is anecdotal stuff--"I did it to mine, and I am happy." The supposed improvements are all just seat of the pants, never quantified. The word that is always used is that the difference is "noticeable." I'm convince that is because people are trying to notice something. If it actually did what people say it does, someone would have posted actual proof in the form of dyno runs, temperature measurements or something years ago. You won't find ANY.
Before you start screwing up the engineering of the bike by randomly changing things, make sure you have a reason to do so. The fact that something is repeated over and over doesn't make it true.
You asked for advice. That's mine. Read what is out there and make up your own mind.
This is a LONG thread, but I suggest you read all of it. You will get both sides of the issue in detail. You can decide for yourself which side you think is more credible. https://www.hdforums.com/forum/touri...eal-facts.html
In another, more recent thread, I challenged the posters to provide real evidence that gutting the cat accomplishes anything and was met with deafening silence. (https://www.hdforums.com/forum/touri...t-removal.html ) All you ever hear is anecdotal stuff--"I did it to mine, and I am happy." The supposed improvements are all just seat of the pants, never quantified. The word that is always used is that the difference is "noticeable." I'm convince that is because people are trying to notice something. If it actually did what people say it does, someone would have posted actual proof in the form of dyno runs, temperature measurements or something years ago. You won't find ANY.
Before you start screwing up the engineering of the bike by randomly changing things, make sure you have a reason to do so. The fact that something is repeated over and over doesn't make it true.
You asked for advice. That's mine. Read what is out there and make up your own mind.
It's not rocket science - remove the material holding heat will decrease the temperature of the pipe at the cat location, thus reducing felt heat by the passenger or rider. Any sound/tone difference is due to the change in air flow characteristics since it is not funneled through the channels of the cat.
It's pretty well understood that performance increase claims are not true based on the reporting Fuel Moto and Fullsac did. The catted pipe flows pretty well, and only removing the cat doesn't show any power gain.
Look outside those that have gutted stock pipes to those who've replaced them with aftermarket headers regardless of brand or type. Many also report reduced heat felt.
If you want the bike to sound different and the header to not hold heat, remove the cat. If you have issues with how your bike sounds or the heat coming from the pipe, then don't mess with it. Simple as that.
Ultimate HDF Member
Joined: Jan 2009
Posts: 5,016
Likes: 277
From: East Tn Foot of The Dragon
Ok first off I know this has been beat to death, but a lot of the info is old or goes both ways. I just got a 2013 SG and NEED exhaust very soon! It currently sounds like a Honda Davidson. I'm still up in the air on slip ons becouse I haven't heard a lot of systems for myself but my real question is concerning removing the cat. It seems that a lot of people have done this and are very happy with the results they have gotten. My concerns go alittle deeper than that. The talk of the o2 sensers not reading properly and leaning the bike out is more more what I'm concerned with. Is this fact or fiction? It's tempting to save the $ and cut open my pipe as I have a friend who could weld it up no problem. I would like to save the money of a new header but not if it is going to cause problems with fuel mapping.
Cruiser
Joined: Sep 2012
Posts: 131
Likes: 12
From: Ottawa, Canada
Before you do it, I suggest you ask yourself "Why?" I have been reading all the threads on this issue for years and have come to the conclusion that no one can show that it accomplishes anything meaningful and that it can, in fact, cause problems, including decal popping and backfires and can screw up how your ECM operates.
This is a LONG thread, but I suggest you read all of it. You will get both sides of the issue in detail. You can decide for yourself which side you think is more credible. https://www.hdforums.com/forum/touri...eal-facts.html
In another, more recent thread, I challenged the posters to provide real evidence that gutting the cat accomplishes anything and was met with deafening silence. (https://www.hdforums.com/forum/touri...t-removal.html ) All you ever hear is anecdotal stuff--"I did it to mine, and I am happy." The supposed improvements are all just seat of the pants, never quantified. The word that is always used is that the difference is "noticeable." I'm convince that is because people are trying to notice something. If it actually did what people say it does, someone would have posted actual proof in the form of dyno runs, temperature measurements or something years ago. You won't find ANY.
Before you start screwing up the engineering of the bike by randomly changing things, make sure you have a reason to do so. The fact that something is repeated over and over doesn't make it true.
You asked for advice. That's mine. Read what is out there and make up your own mind.
This is a LONG thread, but I suggest you read all of it. You will get both sides of the issue in detail. You can decide for yourself which side you think is more credible. https://www.hdforums.com/forum/touri...eal-facts.html
In another, more recent thread, I challenged the posters to provide real evidence that gutting the cat accomplishes anything and was met with deafening silence. (https://www.hdforums.com/forum/touri...t-removal.html ) All you ever hear is anecdotal stuff--"I did it to mine, and I am happy." The supposed improvements are all just seat of the pants, never quantified. The word that is always used is that the difference is "noticeable." I'm convince that is because people are trying to notice something. If it actually did what people say it does, someone would have posted actual proof in the form of dyno runs, temperature measurements or something years ago. You won't find ANY.
Before you start screwing up the engineering of the bike by randomly changing things, make sure you have a reason to do so. The fact that something is repeated over and over doesn't make it true.
You asked for advice. That's mine. Read what is out there and make up your own mind.
Yes it would be good to get some hard data, but a little bit of common sense goes a long way. Just Google "how a catalytic convertor works" and you don't have to be a rocket scientist to figure out that these things work by getting hot. Really hot. They strip oxygen atoms away from nitrogen atoms and the oxygen atoms cause the unburnt exhaust gases to really heat up. They're twice as hot as the exhaust gases that enter them. It only makes sense that by removing them, things are going to get cooler. Both at the location of the catalytic itself, and in the pipes exiting the catalytic.
I think its been acknowledged here that you won't find any real horsepower gains gutting the cat. In actual fact you are now dumping a bunch of exhaust into a big empty chamber. Once again, common sense would dictate there is a little less back pressure and you're going to loose some torque. To many, this probably isn't a big deal. I'm from the school of thought that a properly done head pipe (fuel moto or full sac) is the way to go. The fuel moto web site does have dyno numbers for their head pipe with everything else stock, and there is a 1-2 horsepower gain. Most feel that the $500 price tag isn't worth the $/HP gain. It will however prevent the O2 sensor crosstalk (for those who worry about this).
So yes, it would be good to have hard data, but don't bury your head in the sand and ignore what is just common sense.
Last edited by yowflhtk; May 9, 2013 at 09:56 AM.
Ultimate HDF Member
Joined: Mar 2012
Posts: 6,129
Likes: 143
From: Santa Cruz
If ya are only worried about CAT heat/muffering and/or crosstalk, get a non-CAT '09 header and adapters for your 02s. If ya want performance, get an aftermarket header.
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Elite HDF Member
Joined: Jun 2011
Posts: 3,832
Likes: 127
From: Coastal Carolina
Same question I keep asking....
Elite HDF Member
Joined: Jun 2011
Posts: 3,832
Likes: 127
From: Coastal Carolina
Yes it would be good to get some hard data, but a little bit of common sense goes a long way. Just Google "how a catalytic convertor works" and you don't have to be a rocket scientist to figure out that these things work by getting hot. Really hot. They strip oxygen atoms away from nitrogen atoms and the oxygen atoms cause the unburnt exhaust gases to really heat up. They're twice as hot as the exhaust gases that enter them. It only makes sense that by removing them, things are going to get cooler. Both at the location of the catalytic itself, and in the pipes exiting the catalytic.
I think its been acknowledged here that you won't find any real horsepower gains gutting the cat. In actual fact you are now dumping a bunch of exhaust into a big empty chamber. Once again, common sense would dictate there is a little less back pressure and you're going to loose some torque. To many, this probably isn't a big deal. I'm from the school of thought that a properly done head pipe (fuel moto or full sac) is the way to go. The fuel moto web site does have dyno numbers for their head pipe with everything else stock, and there is a 1-2 horsepower gain. Most feel that the $500 price tag isn't worth the $/HP gain. It will however prevent the O2 sensor crosstalk (for those who worry about this).
So yes, it would be good to have hard data, but don't bury your head in the sand and ignore what is just common sense.
I think its been acknowledged here that you won't find any real horsepower gains gutting the cat. In actual fact you are now dumping a bunch of exhaust into a big empty chamber. Once again, common sense would dictate there is a little less back pressure and you're going to loose some torque. To many, this probably isn't a big deal. I'm from the school of thought that a properly done head pipe (fuel moto or full sac) is the way to go. The fuel moto web site does have dyno numbers for their head pipe with everything else stock, and there is a 1-2 horsepower gain. Most feel that the $500 price tag isn't worth the $/HP gain. It will however prevent the O2 sensor crosstalk (for those who worry about this).
So yes, it would be good to have hard data, but don't bury your head in the sand and ignore what is just common sense.
Since you correctly acknowledge that there are no performance gains to be had and you will likely lose some torque, my question remains--then why do it?
Last edited by TKDKurt; May 9, 2013 at 11:19 AM.