Do you have the part number handy for the amp rack? Do the bolts come with it or do you have to order them separately?
HOLDER FOR AMPLIFIER 1K0035883C
BLACK BRACKET 1K0035933
HEXAGON SOCKET HEAD PANEL BOLT N90817003
EXPANDING NUT N90946001
COVER 1K0971813B (7G8 PURE BEIGE) (9B9 SATIN BLACK)]
the torx bolt and the expanding nut is to bolt the holder to the side body of the car.As you see in the first foto.you will need two bolts and two plastic nuts.
You will need also 2 M6x16 bolts and nuts to bolt the black bracket to the holder.I will tell you to find not hexagonal bolts but something with smaller head for more room for the amplifier to your hardware store.