ngrzan.
Your post gives your email as Bigpond, therefore you emanate from Australia. You also refer to downpipes so – you are probably from NSW or QLD.
How many D/P’s to the house? What is the catchment to each D/P? What is the shape of the roof? are there any reasons for your question, ie asthetics? was the D/P drawn on the plan? did you give clear instructions before the gutters were installed? is there a dispute? What is the Plumbers side of the story?
Bob