the vtec lobe on the s2s2 and the BC4 is identical. the difference in duration specs is probably a difference in where they were measured. duration at 0mm will be higher then duration at 1mm. however, the BC4 has a larger primary lobe giving a little more midrange power over the s2s2 (assuming same setup). for your setup, BC4's will be fine. but they wont idle as well as the s2s2 due to the slightly larger primary cam profile.