The car calls for 91 octane. I usually just fillup at the local station with 93. Just did a fillup with half tank full of 93 with the next grade down - 89. Gas is usually at the local Mobil Station .....never have used no-name gas.
As far as the noise, it may be valve tapping noises ? Can't say for sure....all I know is I hear a consistent *knocking sound* when I start the car if the engine cold and it goes away after 5-10 minutes. I did not notice it last year however, I may not have been so astute & aware of all the noises, performance, etc the car makes since getting HOOKED over at BITOG ;-)