I recommend
Colorplus. They have some standard Porsche colors pre-mixed on the shelf, or they will use your swatch to custom match any color. Follow the instructions close - as with any paint job, prep is the key. This including using their concentrated cleaner.
Gary
2003 Boxster 2.7L - Midnight Blue Metallic, Savanna Beige, Metropol Blue (now owned by son)
2013 Boxster 2.7L - Dark Blue Metallic, Yachting Blue, Blue