I didn't get to spend much time on the ducts this weekend but I did get the mounting points worked out and did some reshaping - still not happy with the top outer corners. Its freezing cold and been snowing here so I did alot of the shaping inside away from the car. it was only when fitting it back on the car I saw the shape didn't follow the bumper recess - the outer corners need to slope less, but they're close enough to do some testing with. I will sort that once I have the rear duct finished. I also had to increase the flange around the edge to prevent a gap around the edge. Now that I have the mounting positions I will integrate the mounting 'ears' into the extended flange. Here's some more pics...