It's duration that causes overlap that makes one set of cams better than another.
B16a cams have fairly high overlap even though duration is less than the GSR.
The GSR engine was designed to feel torquey, so it has less overlap, slightly longer duration, and significantly more lift than the b16a cams.
There are really two options that I have heard that are best for factory cammed turbo B series VTEC's.
GSR cams with stock gears work REALLY well out of the box. No tuning required.
ITR or B16a cams with cam gears and the overlap dialed out <meaning advance the exhaust, and/or retard the intake slightly>. This will cause the valves open period to not overlap so much and make the boost stay in the combustion chamber instead of jsut blowing straight through, and leaving the scavenging effect of valve timing in the dust.
This is all theory, but theory that has been used time and time again with very nice results.
FYI, I am selling my ITR cams for $300, and I jsut picked up a set of decent 80k mile GSR cams for $50. You do the math.
GSR with no cam gears needed = $50 bolt in for power, or $300 + gears + tuning gears?