I wouldn't recommend a filter between the pump and the tank...I'd put it on the pressure side of the pump. If you do run an inlet side filter, use something coarse and with LOTS of area or you risk cavitation. If you pour your fuel into the tank through a screen-equipped funnel, then an inlet side filter on the car isn't really required.
If you can't stand a huge filter on the pressure side of the pump, then a good way to do it is only filter what is going into the motor...that allows a much smaller package because the volume flowing through it is greatly reduced. If you run hat injection for example, you could run a small filter AFTER the metering valve and before your distribution block.
40 microns is smaller that 100. For mechanical injection, you really don't need to use a filter finer than 80 or 100 microns.
I have tested the small cone filters that mount inside a fitting...maybe you've seen them. They work! And believe it or not, they don't change the flow a bit (-8 is ok up to 19 GPM) if they're clean. I just could not imagine that those little things would be ok so I bought a few and did some tests...I was wrong. I run one myself on the -8 inlet fitting to my metering valve and check it before every event.
