The mounting points for the airbox are on the two rear lower corners. One can be accessed through the engine bay; the other is best accessed through the rear wheel arch, and is the one that tends to break, this mount is shown in the pic below:
This pic shows the intact mount (without the nut) ie what it should look like
And this pic shows the broken mount, where the rubber has sheared off, letting the airbox 'knock' up and down
The pic below shows how little of the filter element is used due to the stupidly long pipe Vaux chose to use on the intake
And this is the new system, unbelievably loud!
It does feel better higher up the revs, but tbh the sound is increased so much it's hard to tell what 'real' affect it's had on power - Adrian Flux want me to tell them exactly how many horsepower it's added so really not sure what to say ~5 top end maybe 
One thing is for sure - the grin size has increased that little bit more 
