4 leaf PV springs will RAISE the car at the rear by about an inch, but depending on how sagged your exisiting springs are of course...
On my cars I tend to use the PV 4 leaf, but with the smallest leaf removed... The remaining 2 non main springs are longer than the normal 2 non main springs and therefore heavier, but this does not lower the car. To lower I either turn the smaller tertiary spring upside down, (approx -1") or the secondary leaf upside down (approx -3") , but the preference is yours...
I spent $300 on getting the old Facon springs proffessionally reset and then the car got written off 1 month later, so I don't plan on that again...