James, I like the diffuser, been thinking about similar for my s3, it's got sidepipes, and a gaping hole at the back, is it just screwed to the underside?
thanks Gareth (and Em !)

Yes, a couple of coach screws at the rear into the ash frame and a couple of S/S bolts with washers/locknuts through two drilled holes in the boot floor.
I believe that later Aeros have the petrol tank in the way of the boot floor but I was OK on a Series 1.....
James