200 whp on ctr cams can be done, but not very easily witha 1.8l motor. was your setup bored to 84mm perhaps? yes b16 and itr heads are from the same casting so they have similar combustion chambers, but thats it. its got a mild port job and a better angled valve job like you said, and better cams, valve train, valves, and lma's. the GSR head has smaller combustion chambers. thus, about .3 or so extra compression (i forget exactly how much.)