![[Linked Image]](https://www.tm-img.com/images/2020/09/08/DSC_0064.jpg)
Not a great picture, but here's the rear diffuser on my S4 with side pipes. Not sure if it is different size / shape with rear exit exhausts, also on mine it does run quite a long way forward under the boot to smooth off this area.
As mentioned above, James's S1 has a very nice ally one he's had made up, there are pictures on here somewhere.
With regards to the mesh you ask about Simon, what about matching that found in the wing top vents either side of the bonnet?