Re: 125 octane
Definitely make sure that it is indeed unleaded gas or you'll destroy your O2 sensors (and by the way there are 4 of 'em). Even though these cars are boosted 125 octane needs a ton of compression and ignition power to ignite that stuff. Just heed the mores law here.
I would personally run 100. That is a considerable increase for even the states that offer 93.