Stupidly I fixed the fuel line and brake lines to the floor edge that holds the diffuser front edge into place so first job was to move these up out the way.
Now seems like there are a couple of ways to fit the diffuser, it can either go flush against the bottom edge of the tub or it can over lap the tub with some trim on to cover the raw edge.
Not decided which is the best option yet but it needs cutting about to get into position so will carry on for now.
The job is much easier if you support the diffuser under with some wood.
Thats it for now, will track on tomorrow.