Koolance QDC's... Flow rate

[Five.Stars]

Hi there, I currently have a couple QDC's in my loop which allows me to disconnect the large external radiator for any maintenance etc. Anyway, having bought a couple of new gpu's I am going to have to strip everything down. Having re-designed my loop for easier maintenance in future, I am looking at adding another few QDC's in to the equation... My question, how much do these effect the rate of flow?

I am using a D5 built in to a bay reservoir, currently just have the pump set to setting 1 and everything seems to perform well, but wondering if the QDC's are restrictive to the point I would need to run the pump at higher revs to compensate for adding another couple. My plan is to be able to split the loop up in to 3 seperate parts for easy maintenance. Plan on having QDC's on/ near the inlet and outlet from the reservoir so that I can remove that from the case, a QDC on the inlet and outlet from my GPU's so that I can remove/ replace the GPU's as and when I see fit and also my current QDC's going through case from external rad.

Thoughts?

EDIT: Actually thinking about it, that would allow me to split the loop in to 4 seperate pieces. 1) the reservoir 2) the cpu block and 240 internal rad 3) the gpu's 4) the external rad

 

[Five.Stars]

The current QDC's I am using connecting the rest of loop to my external rad are:

VL3N-F13B

and

VL3N-M13B

the female and male part numbers. They seem absolutely fine just now, but I will be adding another 2 of each, so 4 in total.