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Discussion Starter #5
Thank you for the reply! I was under the impression it would increase horsepower by staying cooler. It must be a back pressure thing.
 

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Lose a LOT of heat on the right. Did not feel any performance change. Exhaust note seemed a bit throatier. DO miss it in the winter though!!!
 

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Any non-factory modifications or parts to ANY motorcycle MAY result in loosing any warranty work on that item/system or other items that may be effected by the modification. But it will not void your warranty wholesale. And if you have a good dealer who understands motorcyclists and how they operate, it will have ZERO effect on any warranty work.
The ONLY change resulting from the loss of catalytic converter material on my Roadmaster was the loss of HEAT! that it emanated.
 

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Lose a LOT of heat on the right. Did not feel any performance change. Exhaust note seemed a bit throatier. DO miss it in the winter though!!!
In Texas we don't have that much winter. Besides, I have the heated seat which is good enough.

I went with the Freedom header so there probably was some HP loss, but I was so happy to get rid of the heat, I am happy.
 

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Discussion Starter #11
I have the heated seat also, it was for the wife. Probably totally unnecessary because of the heat from the CAT, aka furnace. Thank you for the reply!
 

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In Texas we don't have that much winter. Besides, I have the heated seat which is good enough.

I went with the Freedom header so there probably was some HP loss, but I was so happy to get rid of the heat, I am happy.
I ride thru out winter here in Colorado. Never thought of missing it till the first winter without it.
 

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99% of Dealers don't care and don't want to know. The only time it would be an issue is if you had catastrophic engine damage and the factory got involved. You might talk to the Dealer and say "Has anyone taken the cat out of these bikes ?" and see what they say.
 

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Thank you for the reply! I was under the impression it would increase horsepower by staying cooler. It must be a back pressure thing.

Cooler pipes have nothing to do with the engine it doesn't care. A for backpressure that is correct, but technically not. Yes the slight resistance to the exhaust flowing out is commonly called back pressure. But what is really the goal, is exhaust velocity.

Anytime you have 2 pipes or more into 1, the exhaust from each cylinder is flowing at different times to that header (where the separate pipes meet). If the exhaust velocity is high or as we would say optimal as the exhaust from one pipe flows into the header and out the mufflers, it creates a low pressure area in the other pipe or pipes going to the header. This is called scavenging. Because of the lower pressure (less than ambient) the exhaust from the other cylinders is able to move out of the cylinder faster reducing the work the piston has to push it out this increases torque.

Pipes that flow too freely reduce velocity and pipes that are too restricted reduce velocity which eliminates or severely impacts exhaust scavenging. Reducing torque.

Many aftermarket exhaust companies market the "Free flowing exhaust concept" Which in most V Twin engines kill the low to mid range torque.

But when the engine is operating at much higher RPM scavenging is not as important because the volume of exhaust gas flowing out of the pipes needs to increase because the backpressure starts to go up.


So Scavenging helps low to mid range torque. Free flowing helps top end horsepower. V Twin engines live in the low to mid range torque range. Where race engines live in the higher RPM ranges thus the reason for almost open exhaust. When you see the max HP numbers for the Indians, its in the 5000 RPM range. Most of us never go there.

On many higher reving motorcycle engines they actually have a valve in the exhaust system that adjusts back pressure based on RPM to give you optimal low end torque (backpressure) and higher RPM free flowing.

The stock Indian header with CAT gives the best scavenging for the low to mid range torque. The Jackpot header from Fuel Moto is designed to retain the same efficiency of the stock header with the CAT removed.
 
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