BYD serial hybrids with direct top gear have an ICE running 16 to 1 compression,
I posted about it here"
https://ecomodder.com/forum/showthre...6-a-41587.html
The only other place I have seen talk of successfully increased compression without ping is here:
https://turbobricks.com/index.php?th...y-tried.66779/
I would say low hanging fruit is you want your intake charge as cool as you can get it.
In a dry climate; using an Ultrasonic Mist Maker (or Pond Mister) or 10 to produce max mist for per 'space required' for evaporation in the intake may work.