Okay, well they didn't reduce flow on my Eheim 2322 Professional 2 Thermo, so I suppose the model mentioned above is a bigger filter with higher flow capacity.
Wouldn't it be possible to cut more slits in the in-take though? That's how they make them anyway.
To add to this, one thing I liked about this set was the size of the intake - it will actually suck up particles in the water near by, rather than the Eheim intake I got with the filter, where debris in the water would just drift on by, due to the HUGE area of the suction, making it in-effective.
So perhaps these pipes are ideal for my size filter or less only