It was 83.9 for super at my local esso garage this morning when regular UL was 79.9. Petrol will not be getting any cheaper. If I was to run on reg UL it would save me around £600/yr with the current mileage I do(unfortunately not enough to justify another more economical car)

Just what would be the expected performance drop if the car was mapped for regular UL? Car is currently stg1 running around 280bhp.

What would be the difference if the car was running stg3?

Would you also see a drop in response or any other negative performance characteristics other than a drop in pure power.