I know there are some out there who have done it - what exactly is needed, other than the vents? After looking at some drawings it appears that I just need the innner Cayman frames and maybe the clips - right?
.
I just did this to my 2007 Boxster. The inner frames and the vents themselves are all you need. The clips currently holding the frame can be used with the Cayman frames. Looks much better (triple black).
Porsche made the painted side vents a factory option for the 2008 MY (maybe 2007 too). It costs $1,245 (code DAG). Wow! They also include the 2 front air inlets. Still, mine only cost about $175 from BumperPlugs.