ORIGINAL: w8ye
The pipes Konrad has in his picture are pipes within pipes that have a broad torque range as he touches on.The pipes he mentions would be your best bet for all around performance and you will enjoy them.The single cone type pipes as used on all out speed planes and boats have a sharp peak point and are best just used for all out speed.
No, the pipes I show are full wave pipes. The FAI F3D pipe is the pennical of pipe design. The others have a rather long center section between the diverging and converging cones (or reflective washer) this straight section give the pipe its broad RPM band (if a tuned pipe can be though to have a broad band). FYI; the reflective washer is a cost reduction device that actually works rather well. Not as well as the parabolic converging cone but almost and it is a lot cheeper to make! Not that OS gave us any benefit from that in a price reduction!
The single cone "pipe" is really only an extractor. As the exhaust is leaving the engine it is allowed to cool in the cone (expand) causing a pressure drop at the exhaust port to help draw fuel into the cylinder. There is no super charging effect with the singe cone extractors. But there is a narrow tuned intervals that this extraction work .
The dual coned pipes I show all super charge the cylinder at some resonant frequency (RPM).
For more information on how a tuned pipe works give this site a look.
http://www.mh-aerotools.de/airfoils/javapipe_en.htm
Friends don't let friends fly nickel,
Konrad