marcush. wrote:regulations are preventing this in most areas .There is a excluded zone for about anything to be positioned below the step plane (below the sidepods) and of course the centre section of the chassis has to be flat within minium-production-tolerances.
As I understand this area has been exploited recently by Mclaren and RedBull but a rule clrification and narrowing of tolerances has rendered this an impossible area to exploit.
This leaves the area for positioning of turning vanes behind the end of the difusser and below and to the sides the raised section of the high nose /moncoque where not a flat plank is required anyways (plank needs to start at rear of the front wheels and has a specified width).
Well if you mean horizontal diffusion its in use all over, including F1. If you mean something hanging down that will almost always be rules constrained.