If I recall the number right anything over 32 degrees
you start loosing efficiency so if your at 40* your
fuel is burning too slow and needs to be less octane so
you can pull it back... BUT the heads are important
here... a head can be more efficient in itself so
it comes down to what is efficient for your set up...
Don... I'm sorry your brother has this smell fetish
but he needs to get over it and start making power
with less octane... I will say he will make more power
with less octane and it could be moose piss 87 if
he buys from the same place all the time so the tune
can stay the same