IPM, we do also do systemic injections. But if spraying 50' in the air is a problem then I'll have to turn away alot of work to companys with sprayers that can put it up there 75 or more feet. Yes there are times when I won't spray, but really thats a whole nother issue for later.
Lawn Godfather, right now I have a hypro403. I could maybe get a bit more height out of it with an extra large tip for my jd9. But crankn the psi up high enough to do that is'nt worth the possible breakdowns to me. Your right about the GPM and PSI ratio problem. I got a price today on the d813 with control set up to bolt on a 11hp engine for 1466.00. It puts out 21.4 GPM max and 725 psi max. That will get me 60' up in the are. But its a bit steep.
I can get a d503 with controls for 1143.00 for an 8hp engine. The guy that quoted the prices sayed that 50' is about the limit of that pump though.
One of the big expenses is the engines the 8.5 hp is'nt bad My dealer can get me a kholer thats made by yamaha- a nice unit-for 499.00. But the good 11hp engines flot around 1000.00
So I guess i'll have to decide how high my pockets can afford.