[harleyhog]

I've seen these reversion tubes in an auction site.
They say they increase power, increase back pressure, you just 'pop' them in between the head an headpipe.
What's the 'down to earth' view on these?
What does an increase in back pressure achieve?
On my first 'hog' and still learnin!

D.

 

[Sidewalk]

http://www.howstuffworks.com/framed...prime.com/FAQ/Miscellaneous/exhausttheory.htm

 

[HIPPO]

There are anti reversion cones and torque cones, those look like the torque cones.

They used to help midrange torque some on the EVO's when running some pipes. They might help some on TC's if you have a really weird setup, but I would like to see it to believe it. The TC's already have sort of an anti reversion step built into the exhaust ports, and in addition the exhaust valves are smaller.

The only way to know for sure on a given bike is to run it back to back on a dyno with and without them, but I wouldn't hold my breath waiting for an improvement.

The main advantage sometimes can be that they eliminate exhaust gasket protrusion into the port.