Stock Mufflers
Elite HDF Member
Joined: Sep 2007
Posts: 4,928
Likes: 69
From: Near Myrtle Beach, SC
Chief,
In the case of my 2010 Ultra Ltd, the answer is a resounding NO, at least in a stock configuration. I have not measured the stock muffler air flow, but I did measure the air flow from a set of Jackpot Pro Touring mufflers bolted to my stock header (with the cat). I measured the air flow at a distance of 6" behind each muffler tip. I was using a handheld anemometer that I use in my business to measure wind velocities prior to aerial applications of this or that. Again, the header was stock, the CAT was in, and the bike had on it the stock air cleaner.
The results: At cold idle, or about 1200 rpm, exhaust gases were moving at a velocity of 19 MPH from the right pipe, and only 9 MPH from the left pipe. That's measured data, not heresay. So in this test using all stock except for free flowing muffs, the difference was astounding.
Later, I installed the Fuel Moto stainless steel (non-ceramic version) header, Fuel Moto air cleaner, still using the Pro touring mufflers. I use the Rev Precision Performance engine management system. After everything was bolted on and tuned up, I again measured the velocity of the exhaust gases at a point 6" behind each muffler at cold idle, or at about 1200 rpm.
The results: Exhaust gases were moving at a velocity of 29 MPH from the right pipe, and at a velocity of 23 MPH from the left. Higher air velocities from each side, and much closer in velocity than in the stock measurements.
I attribute the difference to the following: Design of the header and the fact that it has no CAT, and also the introduction of a high flow air handler. More air through the engine should equal more air out the other end. I am not sure what effect the Rev Per engine management had on the results, but I suspect that there was a positive contribution there as well.
I made sound measurements as also, but that's for another thread.
Hope this helps in some way. Thanks for your service Chief!!
In the case of my 2010 Ultra Ltd, the answer is a resounding NO, at least in a stock configuration. I have not measured the stock muffler air flow, but I did measure the air flow from a set of Jackpot Pro Touring mufflers bolted to my stock header (with the cat). I measured the air flow at a distance of 6" behind each muffler tip. I was using a handheld anemometer that I use in my business to measure wind velocities prior to aerial applications of this or that. Again, the header was stock, the CAT was in, and the bike had on it the stock air cleaner.
The results: At cold idle, or about 1200 rpm, exhaust gases were moving at a velocity of 19 MPH from the right pipe, and only 9 MPH from the left pipe. That's measured data, not heresay. So in this test using all stock except for free flowing muffs, the difference was astounding.
Later, I installed the Fuel Moto stainless steel (non-ceramic version) header, Fuel Moto air cleaner, still using the Pro touring mufflers. I use the Rev Precision Performance engine management system. After everything was bolted on and tuned up, I again measured the velocity of the exhaust gases at a point 6" behind each muffler at cold idle, or at about 1200 rpm.
The results: Exhaust gases were moving at a velocity of 29 MPH from the right pipe, and at a velocity of 23 MPH from the left. Higher air velocities from each side, and much closer in velocity than in the stock measurements.
I attribute the difference to the following: Design of the header and the fact that it has no CAT, and also the introduction of a high flow air handler. More air through the engine should equal more air out the other end. I am not sure what effect the Rev Per engine management had on the results, but I suspect that there was a positive contribution there as well.
I made sound measurements as also, but that's for another thread.
Hope this helps in some way. Thanks for your service Chief!!
Account Retired
Joined: Oct 2009
Posts: 3,245
Likes: 12
From: Here
I would have to say no. All the Aftermarket slipon's I've used have been different. My Dyna Tuned Jackpots had a smaller inlet for the left side.
I was really surprised recently when I decided to return my RK back to stock, I didn't like the stock mufflers that came on it. I called my local Dealer and the service writer said he had a stock set that came off a 2011 FLHX. They are tapered but have about 30% slashdown end. I was checking them over for scratches and there was a catalytic converter in the right muffler near the inlet. anybody else notice this?
I was really surprised recently when I decided to return my RK back to stock, I didn't like the stock mufflers that came on it. I called my local Dealer and the service writer said he had a stock set that came off a 2011 FLHX. They are tapered but have about 30% slashdown end. I was checking them over for scratches and there was a catalytic converter in the right muffler near the inlet. anybody else notice this?
Cruiser
Joined: Aug 2007
Posts: 205
Likes: 1
From: ATL
I was wondering about this myself. On my '09 UC with OEM headpipe, the stock mufflers (and the subsequent SE Touring slip-ons) had better flow on the left. Now I'm running Samson Silver Bullets and the flow favors the right. Anybody have a good idea behind the engineering involved?
Cruiser
Joined: Feb 2008
Posts: 240
Likes: 3
From: Norman Oklahoma
I am running stock 06 screaming eagle mufflers with 90 degree turn outs that are home made out of 304 stainless. The bike is supper quite and dynoed 100 hp 97 tq.
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Tourer
Joined: Sep 2010
Posts: 294
Likes: 0
From: Lake Ozark, MO.
2010 ultra look in the end of mufflers. Left side seems to have a baffle in the end. More exhast coming out of right to help with anti revulsion form 2-1-2 header. is diffently a difference in which side they go on.
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Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
I would have to say no. All the Aftermarket slipon's I've used have been different. My Dyna Tuned Jackpots had a smaller inlet for the left side.
I was really surprised recently when I decided to return my RK back to stock, I didn't like the stock mufflers that came on it. I called my local Dealer and the service writer said he had a stock set that came off a 2011 FLHX. They are tapered but have about 30% slashdown end. I was checking them over for scratches and there was a catalytic converter in the right muffler near the inlet. anybody else notice this?
I was really surprised recently when I decided to return my RK back to stock, I didn't like the stock mufflers that came on it. I called my local Dealer and the service writer said he had a stock set that came off a 2011 FLHX. They are tapered but have about 30% slashdown end. I was checking them over for scratches and there was a catalytic converter in the right muffler near the inlet. anybody else notice this?
Seasoned HDF Member
Joined: Jan 2007
Posts: 20,616
Likes: 4,440
From: anacoco, la
I was really surprised recently when I decided to return my RK back to stock, I didn't like the stock mufflers that came on it. I called my local Dealer and the service writer said he had a stock set that came off a 2011 FLHX. They are tapered but have about 30% slashdown end. I was checking them over for scratches and there was a catalytic converter in the right muffler near the inlet. anybody else notice this?
not disputing the results, but there has been more than one thread where jamie has said that with/without cat there is not much difference in dyno results.
Last edited by skratch; Jan 29, 2012 at 11:32 PM.