how I see it the bolts go in from the outside, I reckon the inserts are rivnuts in which case you would need a rivnut tool to fit into the wing. What I would do is drill out the plastic offer up intake to where you want it drill the wing then use maybe 6mm bolts and nyloc nuts. Guessing the piece of angle fits on the windscreen panel pillar and the intake bolts to this aswell.
I'm only guessing here mate as I've never fitted one