Dual vs. Factory
Outstanding HDF Member
Joined: Dec 2008
Posts: 2,007
Likes: 353
From: Ohio
Advantage with tru duals over factory? There may be some differences in the sound. But as far as stock engine performance is concerned, there is no advantage. In fact, there will be some loss in performance with tru duals. It won't be a lot. But you'll notice it now and then. That's because the moving exhaust gas in the pipes can be harnessed to pull more air and fuel into the cylinders to produce more power. That will happen only if the exhaust is designed to match the specific engine configuration. Stock exhaust is designed for EPA emissions and noise control first and performance second. If you modify engine components from stock, changing the exhaust from stock to one that matches your mods will make a big difference. But there's more to it than just going to one that's more free flowing. The dynamics of fast moving gas comes into play here. And it's not simple. The engineers use that to design the exhaust system.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
True duals are just drag pipes with mufflers. They can give good power, but over a narrower rev range than many of the alternatives. A 2-into-1 in my case lost me 1HP compared with my previous TDs, gained me a few extra TQ at max, but gave me 15% more low/mid range torque. That is where the real benefit is over other systems. What I didn't expect is that the engine is much smoother running and a darned sight nicer to ride with the system in my sigpic.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
Advantage with tru duals over factory? There may be some differences in the sound. But as far as stock engine performance is concerned, there is no advantage. In fact, there will be some loss in performance with tru duals. It won't be a lot. But you'll notice it now and then. That's because the moving exhaust gas in the pipes can be harnessed to pull more air and fuel into the cylinders to produce more power. That will happen only if the exhaust is designed to match the specific engine configuration. Stock exhaust is designed for EPA emissions and noise control first and performance second. If you modify engine components from stock, changing the exhaust from stock to one that matches your mods will make a big difference. But there's more to it than just going to one that's more free flowing. The dynamics of fast moving gas comes into play here. And it's not simple. The engineers use that to design the exhaust system.
This must be your first Harley.
Is there an advantage to true duals over a stock system? Most certainly. Particularly when paired with a better flowing air cleaner and a bit of a tune-up.
It's a bit more complex and expensive now that there are catalytic converters on every bike, but ANYTHING you put on will perform better than the stock POS system (and likely be lighter to boot).
Last edited by Leftcoaster; Apr 25, 2013 at 01:00 PM.
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