I only use premium fuel. However, I'm still really confused with what people are calling "delay". In sport mode, I get ZERO delay. Instant power. Normal and comfort modes have a little more relaxed throttle response.
So, if there is a desire for quick throttle response......sport and sport+ are the way to go.
Current: 2014 BMW M6 Saphire Black, Eisenmann Race Exhaust (axle-back)
Previous: 2011 BMW 550i M-Sport, Carbon Black, Dinan Stage 3, Meisterschaft GTC Exhaust