This insert has a higer volume / lower compression ratio, meaning better overrevolution characteristics and more top speed. However, keep in mind that this compromises bottom power reaction. The combustion chamber fits the VHM cylinder head perfectly and is easy to change. The last numbers of the part number are engraved on the insert for identification.
Use in combination with VHM head AA33174

– More top
– Best for hard ground
– Quick to adjust

The insert does not fit into an OEM head, only a VHM cylinder head.