Rattling Exhaust Tip
 

Quick tip I thought worth sharing. Just got my latest boxster after a two-year gap (felt longer). And it had the cold start exhaust rattle.

Checked the heat shields, but nothing was loose. Started worrying and looking up catalytic converters online... But then I had another look around the exhaust, and feeling right up behind the cat, I found the sensor that bolts into it on the top - which had come loose and was rattling away merrily! Quick twirl of the spanner and it's right as rain!