As evisc mentioned...textures...however, the model will still be of a higher poly count than the BIS model due to the extra features of the shape of the helo.
Also...just a minor note...the texture you saw in my previous post is a HI-RES texture...ie. 1024....we will be moving to 512 to prevent lag with the addon so although we will try and preserve as much texture detail as we can, the final product may not look as sharp as the pic I just showed.
Pic was more just to illustrate how much time and detail is being put into this bird.