If anyone would be so kind, I have no understanding of how the boost controller works. I am running a mac boost 4 port. The car has already been tuned by mase engineering.

It's on low boost at the moment and target boost is currently at 13psi at all rpms. When I data log it shows it hitting 13 initially but then drops off as rpm rises and usually ends up at 9-10 at redline. My question relates to the boost control table, its currently at 20%, is this 20% duty cycle? im clueless on this table. I'm trying to track down why its loosing boost as rpm rises. I'm confident it's not related to a boost leak.