551 4" Rotors, mostly I20's and TurfBirds, replaced with MP's on 6" MPR heads @ 40 PSI. Should do the trick. Concerned about a few spots spaced poorly at 32-35', but 95% will be golden. Where is the MP4k? Watering window was at 21 hours, could only do one zone at a time on this tap. Now can do two without issue, three is pushing it and compromises coverage. 10.5 hours is acceptable. Great project. 7 guys, including myself, 2 full days, done and done. 32.4 heads per hour with lowering on 80%. I was pleased. We estimated 4 days. Maintenance company was running 3 starts, 6 days per week at 7 minutes each, 2 zones at a time. Mayhaps thats why it looks like a Krispy Kream frying bin; little donuts floating around everywhere. Needless to say, this is my newest account. Next.