slip ons vs true duals
Road Warrior
Joined: Feb 2007
Posts: 1,730
Likes: 199
From: Vancouver BC
i went thru a bunch of dyno sheets with my local tuner when i was originally in the market for true duals. the duals did not perform as well as the stock headpipes on '09 bikes in the lower end of the rev range and performed about the same in the upper end. i decided to stick with the stock head pipes.
the sheets i looked at were for bikes that had just pipes, high flow ac and pc or sert. tuner said the true duals started working better with higher comp motors and cams/head work.
the sheets i looked at were for bikes that had just pipes, high flow ac and pc or sert. tuner said the true duals started working better with higher comp motors and cams/head work.
Road Warrior
Joined: Dec 2008
Posts: 1,639
Likes: 2
From: Australia
I recently asked the same question and a search of the forum turned up some conflicting information, mostly be people who like to speculate rather than actually know, if that makes sense.
I talked to a very reputable and well thought of forum vendor that has an excellent reputation. They recently dyno'd a 2009 SG stock headpipe as well as both dresser duals and V&H power duals on the same bike, same day, same dyno and same dyno operator.
No power gains from the aftermarket head pipes. They could have easily lied to gain a sale as I was ready to spend but instead they gained a customer for life. I LOVE dealing with vendors like that and will continue to do so for a long time, and I like spending money.
I had heard that the 09 headpipes were pretty good, and this confirmed it for me so I just ordered slipons and called it good.
I talked to a very reputable and well thought of forum vendor that has an excellent reputation. They recently dyno'd a 2009 SG stock headpipe as well as both dresser duals and V&H power duals on the same bike, same day, same dyno and same dyno operator.
No power gains from the aftermarket head pipes. They could have easily lied to gain a sale as I was ready to spend but instead they gained a customer for life. I LOVE dealing with vendors like that and will continue to do so for a long time, and I like spending money.
I had heard that the 09 headpipes were pretty good, and this confirmed it for me so I just ordered slipons and called it good.
Banned
Joined: Apr 2009
Posts: 232
Likes: 0
I've Dynoed more than a few Dozen 09's with Stock Head pipes and there hard to beat.. Harley did alot of R&D on the 09 head pipes. Looks ( Heat if you dont tune it ) of the rear Cyl head pipe exiting or the right side is the only good reason to go True Duals ..
Road Warrior
Joined: Dec 2008
Posts: 1,639
Likes: 2
From: Australia
The 09 headpipes are already a 2-1-2, so V&H power duals wouldn't be expected to do anything.
If the folks at Fullsac can be believed - based on their dyno testing, even the stock headpipes on CA bikes (with catalytic converter) do not restrict flow enough to alter performance on a stock TC bike.
The test described above apparently did not include a 2-1 system.
If the folks at Fullsac can be believed - based on their dyno testing, even the stock headpipes on CA bikes (with catalytic converter) do not restrict flow enough to alter performance on a stock TC bike.
The test described above apparently did not include a 2-1 system.
Having said that you are probably right, PDs behind a 96 wouldnt make much difference.
Ultimate HDF Member
Joined: Apr 2006
Posts: 6,913
Likes: 87
From:
Theoretically, you lose power and torque with true duals as compared to a 2 into 1 or the original with crossover. An exception being wide open throttle, big bore drag strip or racing situations. For normal Harley type riding you will probably notice very little difference in any of them, except for sound.
One thing to keep in mind is that if you buy the slip ons now and then decide to go true duals later, the slip ons might not fit the new exhaust pipe. If you think you might add the duals later double check they will still work. Might not be an issue for 09, but it is for 07.
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
I thought TD's may increase HP slightly in modified bikes, but not stockers. In any case TQ in the low-end and midrange will suffer. For most riders of touring bikes this would not be a good trade-off even if there was a HP increase, slight as it might be.
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Road Master
Joined: Apr 2008
Posts: 1,230
Likes: 1
From: Oak Park, IL
I lost 2 ftlb of torque when I went True Duals on my '08. But, the cooler right leg more then made up for it. I did keep a fairly restrictive exhaust on my bike, SE touring mufflers, but the tech who tuned my bike did say that the TDs always come in a little behind stock pipes and a bunch behind 2-1-2 pipes. ( On the '08 )
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