Sigh, I figure I might as well venture into this what if post. IBT setup is a perfect solution for a naturally aspirated car. However, if I was going to do this I would do a shit of research. You will want a free flowing motor with ITB's. That means, you will need to do a high compression piston swap, lightened rods, lightened crank, light weight flywheel, and then get some aggressive N/A cams. Port and Polish job on the heads. No need to upgrade the valves since you won't be flowing as much as a SDS or Turbo.
Now lets say you will have all this done. Now you don't have to worry about a intake manifold etc... or intake piping. However, you will have to get rid of your EGR system, which means your cruise control is gone as well, and if you want really fast reving engine, get rid of the A/C system and get a lightened crank pulley. Anything that will keep this motor high reving and very responsive.
Now with a N/A motor you want response. So that means injector upgrade. You will want peak and hold injectors, they are 3ohm usually and very responsive as compared to a saturated injector that is 12-15ohm. You want response, its a good thing
. So now you are like okay that's not too bad I can do that. Hold up!!!
FUEL MANAGEMENT & IGNITION by far one of the most critical parts in a EFI engine. Now you have 6 ITB's NOT 1! How in the world will you control this the stock ECU, reflash or not is going to take shit when it see's this. And how the fuck would you incoporate hte MAS, ding! So there is NO STOCK ECU, NO REFLASH, NO EMANAGE. You don't have any of those options, what option you have is a standalone. I recommend Haltech best bang for the buck. That's a 1500-2000 dollar expense. With 6 IBT's you will need a Haltech E11v2, the E8 doesn't support 6 injectors in sequential firing order.
So now you are like oh shit, this will cost a lot of money. Yup, but its not it. Now you have to hook in a standalone, its not 1+1 = 2. You will need to find a authorized dealer and tooning shop for this. I spent 2 grand in labor and tuning for my haltech to work as smooth as butter.
If you are up for the challange, I will want to see the results