When I 1st used my blower to treat 10’ tall trees I immediately discovered that when the nozzle end is level witth or above the liquid tank elevation nothing would come out of the nozzle. How stupid! Bought and installed the booster pump and am vey impressed with how my 451 works now with the nozzle at any elevation. The tank contents also recirculate now, very handy when preparing mixes.
Get the pump if you haven’t aleady.
I have not used my unit without the booster pump so I cannot tell you how much of a difference it makes. It is not hard to install. The instructions were not very helpful for a first timer. Wasted a lot of time trying to figure out what they were talking about and the pictures were not good. Would have been nice to see a utube video