You'll need a new frame to mount your double-din head unit into. I used Metra brand's part number 99-9605B. It's a well-made kit that fits and looks like it belongs. I believe the kit also includes a storage cubby to replace the CD holder if you wish to do so.
You can see how I installed my double-din here -
https://rx19jones.wixsite.com/projectboxster/projectboxster-3
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