just bought 02 prox 440 liquid, it has a sticker for 92 or 110 octane but no switch, may have been removed? but the wires are there. has sticker on tach, runs 110 octane. how can i run 92 octane? do i need heads alone or a switch as well? also could i run 93 with octane boost if i stay with 110 octane set up? any thought on what leter for timing, thanks