both method of flow r the same, try turn the 2nd pic 180 degree to right or left...

i think it's best run with the configuration on the left. you already explained it yourself why. coz of the different angles.
the left, you get equal flow restriction on both sides of incoming flow although the differences are pretty minor.

if i remember correctly, the Y-barb i sold u, the top of the Y  is even sharper than a 90 degree angle. probably 60 degrees. i don't think the flow would like that bend, but then again, the differences might be pretty minor.

i had a look again at the pressure drop vs flow graphs of the MCR220 and MCW60
MCR220 at 1.5gpm has a pressure drop of 0.6psi
MCW60 at 1.5gpm is 0.75psi

So based on that assumption, adding another MCR220 to the loop in series is like adding a slightly less restrictive MCW60 waterblock. it doesn't appear to kill the flow that badly.

I'll frankly say I can't say for sure.
we know that higher flow rates contribute to higher efficiency, so with any component, whether the rad, or waterblock will perform better with higher flow rates. however, in general terms, radiators don't benefit from that much from increased flow rates; in fact much less than current waterblocks.

overall flow rates will be slightly higher with parallel rads. thus flow rates thru the waterblocks would be higher. but flow rate thru each of the rads alone will be halved.

in a serial rad setup, overall flow rate is slightly lower, that is, the waterblocks too. but the flow rates thru the rads are now equal to the rest of the loop.

which will perform better you say? to be sure, we're gonna need someone to test for real or do computational fluid dynamics. i'd GUESS with setups with less pump head pressure, running a parallel rad setup will benefit more, whereas with high head pressure pumps, the difference may not be so apparent.
you probably can get away with a serial setup since that's more sensible for your tubing routing needs.

UPDATE:
http://www.xtremesystems.org/forums/showthread.php?t=145954
Read up this thread for further info.
I had totally forgot about the Delta T (temperature differential between water temp and ambient temp) of the radiators, and in this case, parallel wins. radiators are more efficient the higher the delta T is. with parallel rads, both rads have the same Delta T. whereas, with rads in series, the second rad will have a lower delta T than the first because the water temp has already been lowered by the first rad.

err guys...my gigabyte 3d galaxy pump broken already....where can buy nirox p2800 within sunway/puchong/bangi area arr??? any recommended shop???

Can I mix UV Sensitive Ink with Coolant?

Has anyone tried both Nirox and MCP-655 pumps? Does the MCP-655 gets just as hot when it runs like the Nirox?

Thanks bro Well, MCP-655 is 8x more expensive than the Nirox though

hey.. how can i connect MCP355 to 1/2" ID tubeings??
it seems tat MCP355 have smaller input/output connector compare to MCP655.

how much is the head wor??
where can i get it??

i wonder if mcp355+3rd party top will the size bigger than mcp655??

hey, u guys noe how can i get WC in KL? icant find it in KL... i heard my fren said WC is aledi no stocks in KL...isit true?

where can i get the PLASTIC BARB? instead of the brass one.. and how much..thanks..

for me, i think you'll get a better temp "IF":
- your wc stuff is rightly made for high water flow (CPU wb apply!)
- maybe a few drop on your temp via GPU wb