Well I purchased before doing my due diligence on here. After joining and reading up on the pullies, I think the 185 pulley spins the supercharger too close to the red zone for me. There is a noticeable improvement in mid-range with the 185, BUT when you're wide-open there's a lot more heat soak than the 181 which I believe diminishes any top-end gains the 185 has over the 181. In any race you would be over 5000rpm so... what I'm trying to say is the 181 felt stronger on the top-end to me. I'm not trying to get off topic here, just giving you my opinion on my experiences. Hope this all makes sense!