Try replacing all that silicone with hard pipes. A lot of the boost pressure loss could possibly be attributed to how pliable the silicone gets at warmer temperatures. Instead of the pressure reaching the intake manifold, it simply bulges the silicone, causing pressure loss and air flow issues (turbulence, etc)

I know it sounds random but we've had the problem with older dsm's, evo's (reinforced silicone from the factory, bulges under full boost/operating temp)