I have a ninja 500 that I actually like using but seven years later the psi would drop from 500 psi to 300 psi when I pull the trigger. I checked the intake filter and checked lines to see if there is anything blocked which there are non. It used to drop to maybe 50 psi at the most so 450psi. I have the same wand with the same size spray tips. I was about to take apart the pumptec 207 pump to replace the gaskets and piston but before all that what is a normal psi drop for a portable.