4200kms on my Signature and after experiencing 87, 91 vs 93 octane..... IMO, the engine has better drivability qualities using 91 Octane or higher.
At lower revs, I feel the engine is more responsive, has less turbo lag, and is smoother using 91 vs 87.... it feels very apparent when you are accelerating under full boost between 2000-4000rpms. Using 87 the engine's NVH is high.
At higher revs above 4500rpms, the power is noticeably higher while using 91.
For myself, I'm going to only use 91 based on what I have experienced.
At lower revs, I feel the engine is more responsive, has less turbo lag, and is smoother using 91 vs 87.... it feels very apparent when you are accelerating under full boost between 2000-4000rpms. Using 87 the engine's NVH is high.
At higher revs above 4500rpms, the power is noticeably higher while using 91.
For myself, I'm going to only use 91 based on what I have experienced.