The spoon exhaust is not a true 2.5" Exhaust (its a 2.38"), so with your mods i think it could be restricting it.
Although the manifolds good, the Buddyclub and Toda make slightly better gains and would make a difference on a highly tuned engine like yours.
Im sceptical about the readings of the intake, have they watched the intake pressure on an actual live datalog on the road. The readings are only so realistic on a dyno as the fan speed is always constant and )wind speed) never gets anywhere near the speed your achieving on the road. The fan on a dyno is probably good for anything upto 50-60mph but above this your car would actually be getting a good RAM effect in real life, something which a dyno datalogcould not replicate. Considering thats how the Tegiwa (GruppeM)intake is designed to work then it should be tested correctly. By all means they could still be right but im sceptical and it should still be tested in real world conditions before you go splashing more cash on a new intake that might not be needed.
You could always go ITB's
Maybe also consider swapping the RBC for the RRC intake manifold if your after the best gains. You'll get most of your money back for the RBS so it will only cost a small amount extra to get the RCC, much cheaper then changing any air filter(intake)