I bought a 9.5" 4K stall converter from Dynamic as well. They were good to talk too, although the phone calls we had always seemed rushed for some reason...LOL. Anyways, the converter does what I was promised on the phone it would do, so no complaints.

As to how good of a converter it is? Well, I really do not know my drivetrain stuff well enough to answer that...so no idea regarding the efficiency (% slippage), etc, etc...