Don't think Danners are very good for setups with lots of restrictions. On the other hand, this setup may not be amenable to ANY pump that will fit. Tried measuring your actual flow rate? Might be surprised.
I agree with ECU: get some 1/2" barbs and elbows and heat up the ends of the vinyl till it fits over the barbs (boiling water). You can also get some thickwall pvc reinforced 3/8" ID vinyl at home improvement stores that won't kink. Maybe a couple of feet would be enough to remove a few of those 90 degrees.
Why bother water cooling the Voodoo5 and chipset anyway? They are just killing flow with no real benefit (no matter how high you o/c the V5 is is slower than a GF2)