eishozzzz's post was mainly to emphasize the spooling characteristics, that it was beneficial enough to balance out the increase in lag of a bigger turbo
likewise with mike's pointed out the peak boost difference over the curve. Though he did state that with the 2.5" supersplit, he was able to get only 425hp/475tq with C16 at 19psi, whereas he could reach 475hp/475tq with 94 octane after the 3" expansion, also at 19psi. The extra reliability there was also what sold me.