People say that you need an exhaust system for the car to work properly.
But i cant see any reason why you would?
Would the car not work best if the exhaust headers were taken off completly?
Of course it wouldnt be practical/legal plus you would probably get a **** load of exhaust fumes coming through the firewall into the cabin choking everyone inside, but just for theory talk?

As the exhaust gases could escape freely from the exhaust ports without having to fight their way out would it not be best?

I just keep hearing people say you need back pressure, but if so why? i just want to lay this myth (if so) to rest for once and all.

Yes, you need backpressure but not heaps...
It's like getting a hose n puttin it inside a bigger tube....it wont flow as freely as if the tube were the same size...
If no backpressure the exhaust would come out in little puffs not creating a free flowing exhaust as it would have to fight against the inertia and forces of the open air.

drop the exhaust u lose all down low everything, I have done it to test it, gutless down low in the revs but better off up high and you have no engine breaking either. A bit of back pressure is a good thing it makes the system flow, not just expell and turbulate.

The gases flowing in the exhaust form a venturi or syphon effect to draw the gases out quickly.:D

Just take them straight from the engine into the atmosphere through pipes sticking out of your bonnet... like drag racers :D

**** loud too! :P

The gases flowing in the exhaust form a venturi or syphon effect to draw the gases out quickly.:D

agreed, this is what extractors do. they are designed so the exhaust flow of one cylinder helps the other out by creating a small vacuum using the venturi effect.

extractors alone are okish, but when teamed up with a cam that is advanced with longer durations and more lift, they really become worth it.