Using a 90 before return pump inlet?

[sphelps]

Not really, the bigger pipe size the bigger, large enough and the effect will be nil. The hammerhead has a 1.5" I think so you could use 2" inlet piping to minimize effect of 90. You can also use long elbows instead of short.

[1eyedjyde]

I have a 90 about 6" from my snapper hybrid with a 2" inlet. There are no micro bubbles or any cavatation that I can tell.

[daplatapus]

Like Sphelps said, use a long radius 90 or if you have room 2-45's.