So I picked up a bottle of royal purple octane booster to see if it would do anything in our cars. I logged a few runs with timing advance and 93 octane from Mobil and was consistently hitting 24-27 degrees in 4th from 4000-7000 rpm. I then added the octane booster, drove around for about 10-15 miles of typical driving and ran a few logs after the stuff was mixed well with the gas in the tank. Results? After multiple 4tg gear pulls I could only average about 17-20 degrees advance. The car definitely did not like this stuff being put in the tank. I could actually feel it not driving as smooth. I'd suggest saving your money.

 

So I ran the tank down to the fill light and was consistently getting about 16-22 degrees advance over many runs in 4th from about 4k-7500rpm. I then filled back up with just 93, drove for a while and am back to seeing 25-28 degrees advance. Seems to me these cars don't respond well to this stuff. Wish I could have my $14 back but figured I'd post these results.