the only problem i have is bending the pipe to get the pipes woven back and forth.
that is why i have just a signle pipe across teh GPU itself.
Your local home improvement store should have a tubing bender which looks like a tightly coiled spring. The spring keeps the tubing from collapsing when making tight bends. You can also fill the tube with water and freeze it to accomplish the same thing (but more time consuming.
Auto parts stores should care a tubing bender for brake lines also, but you'd probably have to braze the brake tubing to the copper water block.
Also, did you lap the surface of the waterblock after soldering the pipe to it? If not, you probably have some heat distortion that is impacting efficiency.