Can anybody shed some light?.

The inside diameter on the engine side of the manifold is smaller than the diameter at the exhaust end. I heard it gives 30% more power than a staandard manifold.

Its just like exhausts on Go karts & Motocross bikes.

also, better bottom end (more punch) and similar top end to a std header, if not more.

Conical headers help for more cylider scavenging of the burnt gas, they give you more overall power but at a cost, they draw more fuel so you will get more power but can face runtime problems too.

Gracias Hombre !

The conical manifold is beneficial due to the fact that the exhaust gasses "stick" to the walls of the pipes it is travelling in. This stuck layer does not move the same as the remainder of the gas, thus it effectively reduces the pipe size by the thickness of this layer. The layer thickness depends on several factors, density, temp and other reasons.

A conical shape to the pipe massively reduces the thickness of the gasses that want to stick to the pipe walls, effectively increasing the usable internal diameter of the pipe.

is this the same theory of a small water pipe having more internal drag on the fluid as compared to a large pipe?

i didn't understand your above explanation to well

WoW!!

Not really. It is a fluid dynamics theory. The gas closer to the walls of the pipe "sticks" to it, basically increasing the difficulty in getting it moving with the pulsing of the exhaust openings.

im just trying top grasp this concept, so with the conical header opening up as it goes along the gasses that stick to the side move away from the center, removing some of the friction?

It is kind of an involved subject, it is to do with a fluids change in flow properties when it is close to a fixed surface. Have a bit of a read here:

http://en.wikipedia.org/wiki/Boundary_layer

what he said

i know but i cant put it to words
im not a very good writer

Very interesting, and complex!

What I read about conical headers is that, with the small opening in the gas intake, and a larger one at its other end(to the pipe), the gas flow gets accelerated(SP?). That is because pressure difference, if I remember right. The smaller part have more pressure than the larger one, so the gas flows "accelerated" from the high pressure zone to the lower one, to attain equalization with the atmospheric pressure as fast as it can.
Thats why the scavenging process is better on the conical header, it sucks more gas from the chamber, thus getting more fuel on it, faster. Thats also why it will, on a direct with a standard header(consider variables equal, temp, pipe ...) consume more fuel, its getting more fuel into the pipe also.
Thats right ?

(I am very bad with writing too, and that in my mother language, in English then ...)

The conical header works like a ventury, your description is absolutely correct.