Something is wrong with your car. Brand of gas likely does not matter. 91 octane in 60 degree weather should be hitting atleast 30 degrees pretty much throughout the last 2500 RPMS and really should be hitting 32 in 60 degree weather. You are down in the 25 range. Either your spark plugs are really old and its screwing with the ionic knock recognition causing you to knock which you could measure if you had the BT tool. Its worth the expense.
Race gas may mask things and get you to spark at 32 but if it takes race gas to get you to 32 degrees at 60 degree weather that means when it gets 90 degrees out you are going to be back down to 25 or lower degrees of timing. Race gas would be a bandaid. I feel something is not right. BT tool would tell you if your cams are lifting properly etc .
If you spark plugs are new, you measure cam lift and it is normal and you use 91 octane which you are and your air filter is new, I then have no idea why your not hitting withing 8 degrees of timing. I would guess a good 25-30hp is being left off the table across the board which is a lot