ZBrushCentral

edit topo in external application

Some things like stiching mouth I find would be easier doing in 3dsmax…
So i tried process and something is wrong:
-I go to lowest subdiv level, delete higher and export obj file
-select ZSphere, bind original tool in high sibdiv level and under select topo I choose reimported obj file
Even though the file was not yet edited in max I get a head off the scale

What do I do wrong?