Vaporworx / Rick's Tank Problem - dropping fuel pressure at high rpm?

[carbuff]

Tonight while running through some datalogs from my tuning runs this afternoon I noticed something strange. My fuel pressure at the fuel rails is dropping at mid-to-high RPM. I did not expect to see that, so I'm wondering if this would be considered 'normal' or not.

I have a Rick's Tank with the Vaporworx setup, with the (I think) 5th Gen fuel pump / regulator as purchased from Rick's. I'm running a combination of -6AN and 3/8" hardline from the tank to my fuel rails, and my pressure sensor is at the dead-head end of the rail. I'm running a set of 39 lb/hr injectors on the engine.

You can see in the plot below that the AFR as measured is pretty stable, so perhaps my ECU has already 'tuned in' the drop in pressure. But I was surprised to see a 6# drop.

Has anyone else noticed this with the same pump / tank setup? Anyone else surprised by this?

BTW, I only noticed this because, of all things, my ignition timing dropped way down at this time, and I couldn't figure out why. I then realized that the Holley HP EFI setup I have was pulling timing (as I have it set up to do) when the fuel pressure dropped below 53psi. So at least I 'tested' out that functionality...