Originally Posted by Mike Benvo
It depends on the conditions. Depends if the car is achieving its targets on 91 or if it's pulling back ignition.
Some customers request a higher octane tune for when race gas is used.
As I recall my car was retarding significantly on 91. I probably could have stuck with a stock, so called 91-based tune but went with a 93 octane (I don't think 94) version because I now regular blend Sunoco or VP Racing 100 with regular pump 91. I suppose during our current cold weather the performance would have come through even with 91 octane. The good news is that come this summer I should still get comparable performance.
It's a challenge to not bounce off the rev limiter. The nice thing is that doing so is not brutal, just annoying.
2015 BMW M5 Sedan M-DCT w/Competition Pkg and Carbon Ceramic Brakes, Driver's Assistance, and Executive Pkgs, B&O, Alpine White / Sakhir Orange and Black Full Leather, lots of carbon fiber, and a Trunk Monkey called "Der Stig".