Most of the benefit of ITBs are lost once you put a plenum around it. Not saying it won't make the car a little more responsive, but it is basically a waste of time/money on a turbo motor. You won't see the massive mid-range gain you see in NA applications because you have to run the plenum which basically screws the whole power curve up.
Just get a massive throttle body and a decent intake manifold (greddy or something). For all of the hassle/price it costs to run ITBs I'm sure you'll see it is better to just run the aftermarket manifold w/ a single large throttle body.
If you happen to have a way to do some dyno pulls w/ an ITB set up and a greddy+70mm TB set up I am willing to bet you'll either see the same or better results from the singe TB set up. I'd love for someone to have done this and post the different graphs....if I'm wrong I'll edit my post and put lots of these
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