Yes mate. Just cut the hole in the cowel and then mixed up the fibreglass and slapped it on the back. Leave to dry and job jobbed. Probably don't need to but I had the stuff there and thought sod it.

As said mate just a good quality set of amped component up front with a sub. Can't go far wrong with a decent 12" in a box though

This was the setup I had in my A4 until getting the FRST.