I thought I since I was doing this small job on my GT I might as well document it. I noticed a few threads on this before I set out to replace it myself.
From experience I know that the front badges on most Alfas can be a nightmare to remove. Having owned a Phase I 156, a Phase II 156 and a FL 156 TI - and having changed the badges on all 3 - I know all too well that it can be *tricky*. This time my main problem was getting the adhesive on the back of the thing to let go as I prised it away from the structure underneath. Before I started to prise at it I did drench it with hot soapy water and tugged on it a bit to try loosen it. I'd advise anyone doing this to just buy the entire chrome and badge assembly rather than trying to remove the badge from the chrome grille trim - as I can see that ending badly. So here is what to do...
1. Remove the securing allen-bolt in the centre of the rear of the badge/grille cap trim (and I recommend that you immediately put it in your pocket!)
2. Use hot soapy water and tug at either end of the chrome 'wings' to loosen the adhesive (if needed).
3. Using a flat head screwdriver, jam the screwdriver head between the circular chrome collar and the black plastic behind the badge. Slowly prise the chrome trim up and away from the black plastic beneath.
4. Once the chrome trim is pulled away from the black plastic and you can see the locating pins, slowly prise the top area of the chrome trim away from the bonnet paintwork and remove the badge/grille cap trim. Admire the accumulation of filth underneath (mine was horrific).
5. Wash or rub away the dirt and any remaining adhesive from the leading edge of the bonnet.
6. Wipe/polish the area clean. I actually used some T-Cut to get rid of some marks and leave a clean surface.
7. Remove the paper backing from the adhesive pads on the rear of the new badge/trim.
8. Refit in reverse order, align locating pins, slide into position, push firmly to adhere to the paintwork and secure home using the allen-bolt.
9. Shut the bonnet, stand back and admire your handy work.
Anyway - here are the photos... I hope these come in handy for someone...