oh dear lots of people with no swirl pot experiance on here then

Ginge, as you asked the question, simple put, the low level lift pump needs only to be just that, low pressure resonable flow, but no where near what your engine needs, the std swirl chamber size is only one litre, this is great for short term blasts and unless you are going to consume more than one litre of fuel in the time that you are at full throttle then theres no need for it to be bigger, if that is the case then you will need larger reserve, i.e a bigger chamber, and the return from teh fuel rail always comes back to the swirl pot, this then has a smaller bore return back to the main tank, thus keeping the swirl pot at a relativley low pressure, and also to allow air out of the swirl chamber into the main tank where air is no problem(good tank ventillation assumed).

its so simple to do, yet not many do it, ive run swirl chambers for years and never had fuel surge since i started to use them,

HTH