Help me out here.
What are the advantages in using a new 2 into 2 header system (ThunderHeader etc.) over just de-catting the stock header on my '11 Ultra Limited?
What are these "Power Chambers" I'm hearing about?

 

Decatting removes the restriction, however, the design of that opened-up chamber is not necessarily optimal. There may be compromises for making more power, throttle response, low end torque, high-end horsepower, etc.

An aftermarket system will have internal designs or "chambers" for optimal exhaust flow characteristics. There is a science to exhaust flow management, not just straightpipes for most vehicles on the street.

 

the performance advantage is that the bike will go much faster if your wallet is lighter, it takes extra power to move the weight of your money around...

there may be a marginal advantage to an aftermarket system over a stock header w/o cat.
it would likely be realized if huge motor modifications were made.

time and time again is has been shown that the stock header system on a bagger well complements a mildly built motor, cams and maybe headwork.

mike

 

"Power Chamber" is the the name Vance and Hines gave to their crossover in the Power Duals. New fancy name for proven technology.

 

You will get more low end torque because of the "scavenging" affect of the 2:1 pipes. One cyl uses the gas flow from the other cyl to help pull out the exhaust gases so there is less restriction in the exhaust system. On the other hand by gaining low end torque you will give up some top end power, a fair trade off given these behemoths are not made to run like a crotch rocket on the autobahn.

 

Define "marginal"? Like 10hp? More? That's a lot on our bikes. Keeping the stock cats with my Monster Rounds was far too quiet.

 

I'm not sold on the X pipes. That whole idea originated from nascar. I does work on v4,6,8 engines that have constant opposing forces firing but the V twin motor does not run in this fashion. all the dyno charts I have seen are comparing the x pipes to stock head pipes with cats I would like to see a comparison between x pipes and de cated head pipes. For the money and the power gains you have to give V&H credit for some real good marketing.

 

FWIW I ran true duals with Kuryakin crushers which put out 108 hp/113 TQ. Went with MO's which put out 96/111, than I went to Supertrapp 2:1 and now I get 111/115, so there is a difference at sea level anyways

 

The difference between a de-clawed cat and an X pipe is marketing.

You can bet Harley designed the 09 header to be efficient. Then in 2010 they threw in a cat, but it's the same chamber as the 09.

The people that bought in to the Marketing hype of Fulsac and Fuel Moto are going to be adament defending their investments, but in reality, there's no way the added power you will get from them are worth the $450+ you will have to spend for their marketing.

That's the way I see it anyway.

 

If I'm not mistaken, it has more to do with even airflow vs. opposing cylinder firing. Granted there is a relationship but I might be wrong.

I'd like to see proof of a stock cat bike making the same power as a no-cat bike and tuned motor.

We all know there is less heat and more sound as well.