My 410 has SRP forged pistons 5 thou below deck with .028 cometic head gasket with trick flow heads and calculates to 11.5 to 1 compression!
It has 5 speed tremec and 3.91 diff ratio!
I run premium unleaded that is 98 but in Australia we measure our fuel in the opposite to USA ( RON or MON) and I have never heard detonation in my engine and will pull cleanly from about 1000 rpm in fifth gear without complaining and I have a custom roller cam designed by Mike at B3 236.6 / 242.6 and 610 lift on a 112 lobe sep. That cam idles sweet at about 800 rpm with a slight lope but behaves really nice and gets 23 mpg on a run and makes 425 RWHP (about 540 flywheel) and runs low eleven sec qtrs in an Australian Valiant Charger!
If the engine is set up correctly it will not detonate !
It also measures 205 PSI compression on a snap on compression gauge!