I have a newer Hardin marine sea strainer. It is roughly 9 1/2 inches tall w/4-1" npt ports (2 in and 2 out). It also has 2-3/4 inch npt ports on the side. Has half the ports above the grill (as I call it) and half below. As far as the main plumbing, does it matter if I go in above the "grill" and out above, or in below and out above or whatever? Also, should I use one of the 3/4" ports and run a line out the side of the boat to blow water out to relieve pressure or not? Help please and thanks!

In the top , out the bottom that way you just take the (grill) out and clean it .And if you did not have water pressure problems before you still don't. You can not leave an open fitting or the pump will just suck air. hope this helps