I bought the OEM kit from Kioti which basically allows to install an extra double acting valve assembly. My tractor came with one set of valves in the back. The installation involved taking off the valve cover from the OEM valve assembly, install longer bolts, and add a second double acting assembly (#1 in the schematic below) next to it. It is positioned just under the driver's seat, to the right. I attached the installation instructions that came with the manual as a pdf file. Slide 1 provides a quick overview of the system. Here's a screenshot, further details attached :
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