it definitely says premium recommended.
but so does our GMC denali and we have run 87 for the last 50K miles without any issues.
i get the porsche isn't the same as a GMC but also dont feel the V6 porsche is on the same level as most other porsche when it comes to performance
will probably go ahead and run premium but wanting to get some ideas of issues 87 would cause
so you have the 6.2L in your GMC?
I have that engine in my Silverado...hook up a scanner and watch spark retard. With regular gas you will get double digit spark retard numbers under acceleration. With premium it will drop to single digit numbers...with E85 it will have full ignition advancement. Clearly there is a huge difference in performance/efficiency with higher octane fuels. I would predict the same is for your high performance Porsche, which is most likely pushing that timing even harder to get the most out of the engine.
if you don't care about max power and efficiency...run whatever you want.
3 of the four cars in my signature require premium, and only get fed the best. The X lives on whatever is cheapest ;-)