4gpm direct drive repurposed

I have a Dewaltt direct drive 4gpm 3900 psi w 13hp Honda 100 hr or less on it. Great machine helped to get me started ! I have moved up to 8gpm machine My question is, if I have the direct drive fed off the low end of 200 gal buffer tank will it preform like it did, tied into water source ? Or should I change out the pump? My goal is to use it with a hot box.

I used a 4/4 direct drive for a while and fed it off a full buffer tank. It worked, but made some weird noises, obviously not optimal.

His pump made weird noises because it was likely starved for water. To make this easier and avoid any issues your definitely best off replacing the pump.