Bet all those right angles on the piping curtail the flow of water. Although I do like the double intake section on that unit with the 2 strainers, I believe the more surface area for the inlet pipes the better as this will help maximise flow intake IMHO. Only a theory on my behalf but I bet its not too far off the mark without having tested it.
Ehiem do an intake/outlet set that are modular but not quite the same. I agree with Zigs' comments though about the bends. A recent test done in a Koi Magazine (Koi Nations) found that swept 2" bends gave a 12% improvement in flow when compared to 90 degree 'knuckle' bends. 12% is a big difference IMO and it makes me think about how much we restrict flows in tanks and ponds. I have to admit I'm looking at my pond filter return with an eye towards being more efficient.