458 speciale rear spoiler

The short answer is no.
Not a simple bolt on procedure.
I checked.
The top edge of the Speciale bumper under the spoiler is higher than the stock Italia. So, spoiler/cap will sit above the stock Italia piece if you placed it on top of the standard Italia bumper.
Net, you have to do entire bumper AND exhaust. Looking at something like $25K for the bumper, spoiler, and exhaust!!!
I passed without thinking twice.
I have always wondered why someone didn't do a carbon fiber piece that you could place over standard piece to give the same look. After you painted it of course.
Best

 

A photo would help Randy !

 

Mel,
I am a dinosaur when it comes to technical skills on a computer. I have no idea how to post a photo in general. Let a lone one of something that hasn't/can't be done.
I will try and use my best linguistic skills to describe the dilemma.
If you look at the back of your car, above the cavallino is a seam that runs the width of the car. That cap which houses the CHIMSL (US Dept of Transportation speak for: Center HIgh Mounted Stop Light) is fused to the bumper below it.
Thinking of the Speciale, its rear vent that runs the width of the car -and makes up the leading portion of the bumper top edge-sits higher than the seam on our cars. So, If you were to put the Speciale CHIMSL piece on a 458 rear deck the 458 bumper sits too low for the Speciale piece to "touch"/mate up with the standard 458 portion below it.
Hope that makes sense.

Randy