2007 Porsche Cayman — open carrier or enclosed for a normal enthusiast car?

Write down what you already tried. A second data point from another 2007 Porsche Cayman owner helps more than a generic diagnosis. That's where I'd start. Run the total, not the monthly, before you commit. I'd rather be boring and correct. This is the version I'd tell a friend.

Don't overfit one forum story to your car. If it still isn't clear on the 2007 Porsche Cayman, a specialist hour can be cheaper than another round of parts. I'd do that before spending real money. If it doesn't change the out-the-door or the repair estimate, it's noise. If the story changes I'll post the new data.