Here is a little money saving tip...
The rear boot badge for the Brera is the same size as the 159 but the plastic mount is completely different. What i did was to by a genuine 159 badge which is up to £30 cheaper and remove the centre metal emblem and re-fit it to the original Brera mount.
The metal emblem is held in to the mount with self adhesive form so to remove it I carefully heated the badge with a paint stripper gun (or hair dryer for those who still have hair), being careful not to over heat. This helps release the glue and the emblem can be eased off.
I recommend you try this first on the old badge, take care not to scratch the plastic mount when removing.
Use some double sided adhesive on the mount and metal emblem and re-assemble shiny new emblem into the original mount.
The whole job took no more than 20 minutes