Low pressure drop blocks?
 

I'm in the process of getting my system together, and I've been looking for info on the pressure drop of a few blocks with no luck.

I have an RBX right now, and I'm looking at adding NB and GPU cooling, but I want low pressure drop blocks to make sure my rbx still runs ok.

I know the Maze4 Chipset, and Maze 4 GPU are supposed to be good, but what about the older DD blocks, like the z-chip? I've also heard good things about the silverprop HL/SL blocks.

Any help is appreciated. Thanks.