The black plastic clips are for my wheelchair, just fold the back rest down and push the wheelchair into place, give it a little shove so the foot plate locks into the clips and pull the bungy cord over to a support under my wheelchair and clip it on and the wheelchair is locked into place, takes about 5 seconds once the wheelchair is sitting on the deck.
The standard muffler was replaced with the one in the pic, it is a high flow sports one and now sounds as it should.