Intercooler maxed out? hitting an invisible horsepower wall on dyno

Hey guys, let me begin by going over my setup briefly

S6 RX7 FD, freshly street ported engine, Haltech Elite 1500, Precision 6266 GENII, Tubular manifold, Tial 44mm MV-R wastegate. AEM water/meth 1000cc nozzle 50/50 mix, CXracing V-mount intercooler.

so after returning from the dyno, we seem to be hitting a "wall" where the power is maxing out at around 385whp, even adjusting boost from 16-22PSI yielded almost NO results. other than that engine seems to be running very happy, AFR's are staying consistent and in the mid 10's. my tuner believes that my intercooler is maxed out and isn't flowing the amount of air needed, is this possible at these power levels? what are the tell tale signs you are "maxing" out the intercooler.

for reference this is the intercooler i am using

https://www.cxracing.com/products-by-car/products-by-car-mazda/products-by-car-mazda-rx-7-fd/KIT-FD-V

Regards,

measuring the pressure pre & post intercooler will tell you how restrictive it is.

What intake air temperature are you seeing at your different boost levels?

What fuel are you running to be keeping it into the mid 10s?