Most of Spinner's stuff starts around 300 bucks IIRC
When I called and talked with them, they said they recommend it for Cummins 5.7L, and larger, and felt like perhaps the CRD was too small.
The issue is that they run parallel with the Oil filter/cooler circuit, not series, and need to maintain enough flow to maintain proper pressure, when the centrifugal oil cleaner is pulling oil pump volume from the engine while it's running.
Some of this powers a high speed hydraulic motor that spins the centrifuge.
The rest is processed through the centrifuge, and returned to the sump along with the oil used to power the motor.
http://www.spinnerii.com/index.cfm/lev1/726/How.The.Centrifuge.WorksWups, I see they've changed their design a little, and now use post-centrifuge oil to power the motor. Much better than the one I looked at before