Your right there Jeckle - it's actually a limitation of the hexidecimal
ECU data the CPU provides that limits the maximum boost measurement to 18.45 psi.
As most standard Subarus were designed to boost 15-16 Psi Subaru obviously thought there would be no chance of boost spikes greater than 18.5 odd. As such, the car could be boosting higher than 18.45 but I'll never know using the data scan.
What I can advise is that it seems that the much higher torque seems to be causing the engine to twist on its mounts much further and may be fouling the dump pipe again. Either going to be looking at stronger engine mounts or another slight modification of the dump pipe.
Oh well ... The joys of modding.