the spray out of the tip just isn't even. i did my calibration test on the driveway. it is heavy on the left and right side of pattern not to much going down in the middle. everything is new, there was nothing clogged. i am getting .5 gallons per 1,000 sq. ft. with yellow low volume tip and the 25 psi pressure regulator that came with my backpack. i just got a constant-flow valve from gemplers (21psi RED). but need to figure out what would be an ideal tip for this situation? any suggestions would be very helpful.