Bob,
I made the same upgrade last July. In a nutshell - couldn't be happier. 2006 Cayman S.
Believe me - there are going to be days where you will MISS the sound of the air-cooled flat 6. You will be flooring it in 3rd and wonder if there's something wrong with the engine - it doesn't sound like you're on the front of a super-turbine.
Definitely look at an exhaust upgrade and intake upgrade (with SofTronic flash). The flat six just sings with the right exhaust and intake on these. The fun-factor increases too
