I am considering adjusting timing slightly for a slight power bump. My 87 RX7 GXL is all stock drivetrain. I run 89 octane typically but could easily do higher if necessary. Reading some threads out there already, it looks like leading at 5 degrees after TDC is typical base stock timing. I have read a variety, but it sounds like 4-5 degrees BTDC for the leading tends to be a safe and helpful adjustment. Is that fair to say? Anything else I need to know?