This board is full of high performance experts, so I need to ask..
Is a de-catted head pipe equal to a Cobra Power Port or S&S head pipe, Power Duals or 2/1 set-up?

I noticed that the cross over pipe on the stock system and Power Duals are flatted out and the S&S / Cobra's are round.

I seems the 2/1s are the choice of high RPM addicts.

Thanks in advance for your experience.

 

The only time you need to mess with the cross over is a really big build. In fact for many increasing flow on cross over could work against you. Fuel moto offers a higher flow cross over. They have some good info on the subject on their sight,
Heck Fuel moto has good info on just about any thing.

 

as with an intake, it is possible to put on a larger exhaust* than is good for a particular motor.

all the parts have to match to get best results from the whole system. and the keys are to manage flow of gasses and the velocity of that flow. and for better results, also affect or tune the pulses of exhaust in the tract.
the intake and exhaust should match and complement the heads and cams.
often a longer exhaust and or intake will give better torque...a short tract gives better HP

for a near stock motor, a decatted stock header is suitable and costs much much less than an aftermarket "performance pipe"


very generally;

a 2/1 will help low rpm torque- but high rpm HP may be less than other systems. a 2/1 will usually have tuned equal length header pipes which allow scavenging.
the overall flow will at some point be limited by the size of the pipes at the junction. an overly large pipe will give poor velocity

a 2/2 will often have less power at low rpms ( no scavenging) but may make good power at high rpms.

so we ask where do you ride more? 2500 or 5500 rpms

one pipe design may be a better match than the other based on that


the 2/1/2 is a compromise and has the headers connected so there is some scavenging for low rpm pull, and the overall exhaust system has high volume which allows high flow and good exhaust velocity.
at lower rpms it will work kinda like a 2/1, most of the flow goes out the right side. as the flow increases, the left side relieves pressure build up and becomes more active ( which a 2/1 can't do)


the high interior volume of the touring exhaust tract is a real plus - but it won;t fit on a smaller framed bike.
the same Harley A motor is used on both the Touring and Dyna lines- dyno charts usually show a gain of about 3 hp when this motor is used in a touring bike,- the difference is the exhaust.

so on a smaller framed bike a 2/1 is often a better fit/choice for power.


my CHP FXRP was built with a cammed pursuit motor- these actually had the evo touring exhaust matched to the bike with a 2/1/2 header and a shortened version of the touring type mufflers hanging off the police saddlebag mounts.
in 1990 I put on a tuned 2/1 which gives good low rpm power- I was able to switch the final to a 15% overdrive. and saved about 15 pounds of weight

2/1 & 2/2 are great for specific needs- a 2/1/2 will give good results across a wide rpm range.
and for $150 on ebay, a decat is the value leader

my '53 FLF uses a stock 2/1 pipe, my 2009 FLHTC uses the stock no cat header- the motor is stock.

mike

* one of the loudest bikes I ever heard was a dyna with short straight pipes- he made no torque and had to rev and slip his clutch just to get moving from a stop- in normal city riding he couldn;t keep up with my stock 38 HP panhead

 

2-1 will work at any rpm they are sized for, just like any other exhaust. Pro stock motorcycles use 'em, they are upper rpm performers to be certain.

 

In a word: NO.

 

OP didn't mention Rinehart Slimline Dual, or True Duals, that all the pipe & muffler manufactures make.

Plus 1 what mkguitar said.

 

Thanks for the information. I am running the 2/1 set-up and very happy with the performance. But there are times I miss the look of the dual exhaust from behind. I had a local opportunity to pick a use set of High Outputs but needed a head pipe, but was scratching the idea of the de-catted system that I have stored away in the attic.