I run a 440 source, it flows enough to keep my 512, that has an engine bay packed with roxul insulation and mud, has the radiator in the bed of the truck and 10ft of hose to get there cool.

They fixed the small passage problem a long ago, so unless you have an super old one I wouldn't worry about it. They do still have some blemish ones on their clearance items page if someone still wants to complain about them.