I think the Star pump is very nice quality but on a quieter street car annoying from the vanes -clack -clack -clack -clack.....

Second to that, the regulation of pressure was at the pump itself but they recommended using a separator between pump and engine. Soooo, as the foam media gathered oil the amount of vacuum between pump and separator remained at whatever you set it at, but between separator and engine would quickly go from negative to positive as the media became more restrictive. I felt with that design the regulator should have been on the hose between the separator and engine (as to maintain negative pressure on the crankcase consistently) but Star did not agree. (so I moved on)

Now using a GZ pump as it has more of an oem appearance and is quiet.