diff --git a/src/main/java/com/sk89q/worldedit/blocks/BlockType.java b/src/main/java/com/sk89q/worldedit/blocks/BlockType.java
index 6f37eb902..96c22df77 100644
--- a/src/main/java/com/sk89q/worldedit/blocks/BlockType.java
+++ b/src/main/java/com/sk89q/worldedit/blocks/BlockType.java
@@ -348,7 +348,7 @@ public enum BlockType {
         shouldPlaceLast.add(BlockID.CARROTS);
         shouldPlaceLast.add(BlockID.POTATOES);
         shouldPlaceLast.add(BlockID.WOODEN_BUTTON);
-        shouldPlaceLast.add(BlockID.HEAD);
+        shouldPlaceLast.add(BlockID.ANVIL); // becomes relevant with asynchronous placement
         shouldPlaceLast.add(BlockID.PRESSURE_PLATE_LIGHT);
         shouldPlaceLast.add(BlockID.PRESSURE_PLATE_HEAVY);
         shouldPlaceLast.add(BlockID.COMPARATOR_OFF);
@@ -452,7 +452,6 @@ public enum BlockType {
         canPassThrough.add(BlockID.CARROTS);
         canPassThrough.add(BlockID.POTATOES);
         canPassThrough.add(BlockID.WOODEN_BUTTON);
-        canPassThrough.add(BlockID.HEAD);
         canPassThrough.add(BlockID.PRESSURE_PLATE_LIGHT);
         canPassThrough.add(BlockID.PRESSURE_PLATE_HEAVY);
         canPassThrough.add(BlockID.COMPARATOR_OFF);
@@ -493,20 +492,36 @@ public enum BlockType {
         centralTopLimit.put(BlockID.ENCHANTMENT_TABLE, 0.75);
         for (int data = 0; data < 16; ++data) {
             if ((data & 4) != 0) {
-                centralTopLimit.put(BlockID.END_PORTAL_FRAME, 0.8125);
+                centralTopLimit.put(-16*BlockID.END_PORTAL_FRAME-data, 1.0);
             }
+            else {
+                centralTopLimit.put(-16*BlockID.END_PORTAL_FRAME-data, 0.8125);
+            }
+            centralTopLimit.put(-16*BlockID.HEAD-data, 0.75);
         }
+        // Default value to be used if no data value is given
+        centralTopLimit.put(BlockID.HEAD, 0.75);
+        // Heads on the floor are lower
+        centralTopLimit.put(-16*BlockID.HEAD-1, 0.5);
+        centralTopLimit.put(-16*BlockID.HEAD-9, 0.5);
         centralTopLimit.put(BlockID.FENCE, 1.5);
         centralTopLimit.put(BlockID.FENCE_GATE, 1.5);
         for (int data = 0; data < 8; ++data) {
             centralTopLimit.put(-16*BlockID.STEP-data, 0.5);
             centralTopLimit.put(-16*BlockID.WOODEN_STEP-data, 0.5);
+            centralTopLimit.put(-16*BlockID.SNOW-data, 0.125*data);
+            centralTopLimit.put(-16*BlockID.SNOW-(data+8), 0.125*data);
         }
         centralTopLimit.put(BlockID.LILY_PAD, 0.015625);
         centralTopLimit.put(BlockID.REDSTONE_REPEATER_ON, .125);
         centralTopLimit.put(BlockID.REDSTONE_REPEATER_OFF, .125);
         centralTopLimit.put(BlockID.TRAP_DOOR, 0.1875);
         centralTopLimit.put(BlockID.SLOW_SAND, 0.875);
+        centralTopLimit.put(BlockID.COBBLESTONE_WALL, 1.5);
+        centralTopLimit.put(BlockID.FLOWER_POT, 0.375);
+        centralTopLimit.put(BlockID.COMPARATOR_OFF, .125);
+        centralTopLimit.put(BlockID.COMPARATOR_ON, .125);
+        centralTopLimit.put(BlockID.DAYLIGHT_SENSOR, 0.375);
     }
 
     /**
@@ -517,12 +532,12 @@ public enum BlockType {
      * @return
      */
     public static double centralTopLimit(int id, int data) {
-        if (centralTopLimit.containsKey(id))
-            return centralTopLimit.get(id);
-
         if (centralTopLimit.containsKey(-16*id-data))
             return centralTopLimit.get(-16*id-data);
 
+        if (centralTopLimit.containsKey(id))
+            return centralTopLimit.get(id);
+
         return canPassThrough(id) ? 0 : 1;
     }