A while back I said I was amazed at how the car ran on Shell Super. I ran 3 full tanks of it and it never skipped a beat, pulled hard and steady, and got good mileage.
Switched back to no name super and the car is sputtering from idle through 2300 rpm, uneven boost and not full at WOT, roughly the same mileage.
My test has confirmed for me that not all gas is the same and, for me at least, I will stick to a name brand gas.
Who regulates what octane these stations put into their tanks?

they were testing to see if octane adders really did anything, but they used (i think) shell ultra 94, they used a CFR engine which is what the octane ratings are based on and tested it and it really was 94 octane. I dunno who regulates that stuff, but i'll agree my audi runs like crap on some fuels, luckily wal-mark gas seems to be pretty good, and its the cheapest, ha. My bmw which supposedly requires 89, seems to run great on just about whatever.

Search this forum and Google for more octane info. Europeans use RON numbers; US uses "pump" (RON + MON / 2), which in practice is 4 to 5 units less than RON.

but its a 10.5:1 NA motor with 4 knock sensors, so really it shoudl be capable of retarding a bit if there was some poor gas, and the 290hp probably allows me to not even notice a slight loss in power or what not.

Sunoco race fuel at 105 octane is always available for super motors...