I realize that the added cost of premium over regular should be considered a worthwhile "cross to bear" in the operation of performance engines. Yet, I'm by nature sensitive to the cost differential, mainly to the change in the premium pricing of 93 octane vs 87 octane. Anecdotally, in the SE US the difference 15 yrs ago was perhaps 5% ($2.10 premium vs $2.00 regular). The differential has risen steadily since 2008 or so to 25% or more ($2.50 premium vs $2.00 regular). I am curious as to the performance and longevity compromises affecting turbo applications using 87 octane instead of 91+, as I have used in the past 20 yrs running BMWs, VWs and Saab and Volvo turbos.
As an example, the VW TSI turbo application specifies 87 octane. Is this system then essentially a neutered turbo application, in which the ECU map's top priority is to resist/minimize/prevent detonation from occurring, and realizing whatever (increased) performance the turbo provides under those constraints?