I've logged into both the normal 3Racing website and the wholesaler side and don't see this as being mentioned as being anything different than what comes on the kit. They usually put that in their "Articles" section. Still looking at the pic posted earlier it still looks just like the stock motor mount. The stock one also has the spur gear side screw hole lower than the other side.
Looking back at the website I think I can see where the confusion is. There is a motor mount listed under the "option parts". But if you look through the parts listed there you will see that 3Racing lists all their parts under "option parts", both stock and aftermarket parts. Reading the description of the motor mount show there says "Motor Mount is one of the standard parts of SAKURA ZERO". And the pic shown there is the same as the one posted earlier in the thread.