This quite simply shows that the internet is a terrible place, but a fantastic example of 'a little knowledge is a dangerous thing'.
The typical attitude to 'porting' is bigger is better, and that is a very 1970's thought process. With airflow management (which is a better term for what we are aiming to do with cylinder heads/induction systems) the aim is to deliver the required air mass at the correct velocity with the least pumping and efficiency loss. Does this mean honk out as much ally as you can? If your a simpleton yes.
Big ports mean one thing.........for the finite level of mass that the stock inlet manifold can deliver, which will be no more than a few percent between variations, you will have a lower air speed index in critical areas......and quite simply put, that means lower cylinder filling.
Why do I not 'port' (god I hate that term) the whole length?
Because it is counter productive and gains nothing. I have done enough of these manifolds and invested enough time into preparing a modification which provides all that is required and converting it to a CNC process. If you wanted the whole runner done, expect higher prices and less torque.......and maybe 1-2bhp peak extra. And as far as I'm concerned.....2bhp peak is of very little use when the ratio of torque change is higher than the ratio at lower rpm in a higher gear......simply put....less m/s2.
The RS manifolds are larger throughout yes.......but they also tend to make the least torque out of all the 'finished' modified manifold combinations, as they lower airspeed around the critical bend in the manifold. So just dont be one of those internet people who's thought process go about as far as 'oooh its shiny all the way through'.
In high level motorsport, your likely to be fired for wasting company time 'cleaning up' a rough cnc finished inlet/cylinder head.