Each cable in the phaseing harness that is cut correctly will result in an additional 6dB of rejection each. The cables should be 1/4 wavelength electrically, so you will need to look up the velocity factor of your cable and use it to calculate the lengths. The lengths should be to the center of the tee, which should also be calculated in to the equasion if you can find the velocity factor of the t.
Sinclair takes the aproach of eliminating the T and using special connectors that work like a T with the coax going in the sides. This can be emulated by using thin coax like RG-223 and drilling some holes in the side of the connectors.
