Cathar said:Wow - talk about digging up an old thread eh?
The newer muffled D4's are substantially weaker than the original loud D4's. In fact, the newer muffled D4's (MCP650) are no longer more powerful than the old Swiftech MCP600 excepting in very low restriction setups.
The newer D4's do still whine to a noticable extent, but it is not as loud as the original pumps. Some people claim that the pumps are quiet but this is, as always, a relative and often subjective thing.
I'll be doing a full comparison of the 12v pumps I have at my disposal as soon as my latest baby arrives. Sorry, I do not have the CSP750 pumps at my disposal, and nor am I particularly interested in them. I have an inherent distrust of anodised aluminium, no matter what a manufacturer says. Anti-corrosion additives also only serve to lower the thermal properties of water (also regardless of what a manufacturer will say), and so I don't personally consider anodised aluminium products with corrosion inhibitor as an acceptable situation - but that's just my opinion - people's are always free to disagree with me.
Here's something I posted at Procooling.com about the new pump I have coming:
Hey Cathar where did you find this pump at? I'm looking to replace my two MCP600s. Iwakis are too big and this pumps looks perfect size wise. Waiting for your results and hopefully they turn out well.