What octane should I run
At 11 to 1 or less = I run C11 but it is more expensive
for some crazy reason.
Higher compression than that I run C12.
The timeslips will tell you what your car prefers.
However, different fuel often takes a bit of experimentation
with Jetting and timing to optimize you combination.
But it is not a big difference.
But I won a class race in stockagainst another 340 at Denver Nationals
by .0001 true margin, bracket racing is not near as critical.