You're correct, the 185 will be making more boost/power than the 178 at any given rpm. That being said; here's the real question you have to answer:

If you are going to be driving the car more than racing it, ie, around town, stop and go, then get the 185 because it has a significantly stronger midrange and is more responsive and torquier. However, if you are going to regularly drag race the car, or do top speed runs, get the 178 instead. There is a yet-to-be-solved problem with the 185; be it octane, timing, heatsoak, spark, parasitic loss, etc... but the 178 is faster at the track than the 185. That being said, if you will be only racing once in a while, get the 185.

I have a C32, I've owned both pullies, and I don't care what loungn14 has to say. He is an outlier on a graph. Many of the crossfire srt6(same engine) guys are a lot faster than him anyways, and of them 90% of the fastest ten cars use the 178 pulley.

HTH.