Unity 3D asset post process split fbx into separate prefabs

using UnityEngine;
using UnityEditor;
using System.Collections;

public class AutoSplitFBX : AssetPostprocessor {

    void OnPostprocessGameObjectWithUserProperties (GameObject go, string[] propNames, System.Object[] values) {

        for (int i = 0; i < propNames.Length; i++) {

            string propName = propNames[i];
            System.Object v = values[i];

            if (propName == "UDP3DSMAX")
            {
                // max exports all props as single string. we must split by return char
                string[] lines = ((string)v).Split('\n');

                foreach (string line in lines)
                {
                    string prop = line.Trim();
                    Debug.Log (prop);

                    if (prop == "splitfbx")
                    {

                        string path = System.IO.Path.GetDirectoryName(assetPath);
                        string assetFileName = System.IO.Path.GetFileNameWithoutExtension(assetPath);
                        System.IO.Directory.CreateDirectory(path+"/"+assetFileName);
                        string prefabPath = path+"/"+assetFileName+"/"+go.name+".prefab";
                        Object targetPrefab = AssetDatabase.LoadAssetAtPath(prefabPath, typeof(Object));

                        if (targetPrefab != null) {
                            PrefabUtility.ReplacePrefab(go, targetPrefab, ReplacePrefabOptions.ReplaceNameBased);
                        } else {
                            PrefabUtility.CreatePrefab( prefabPath, go );
                        }
                    }
                }
            }
        }
    }
}