What makes your motor a 2.0 GSR? And who told you to go back to GSR cams? lol.. Let me guess, someone that has GSR cams trying to talk you into trading because you'll make more power on the GSR cams then the ITR's?

One thing you could do is compare the to on a dyno. But keep the ITR cams, they make more power easily. The GSR will make more midrange power, but as the looks of it your head will handle higher RPM's, so I'd defiantly stick to the ITR's most people make at least 20-40 WHP more with the ITR's.

Honestly I can't find much on the turbo you picked up so I'm kinda blind in this situation. From what I found online the hx35's and hy35's are making 300 with ease. Do you know the compressor size or the exhaust housing size for that turbo? Either way you'll be happy with a boosted motor regardless of how much power you make, even if you hit 300.. After a month or so you'll be wanting more.