this should be sticky'd up!, , Nice info!, So 300M Special Owners are using Premium fuel for nothing?, lol, or...?
Probably the computer on the special has a more aggressive timing/fuel map. I know the 1st gen 3.5 originally had a 10.5:1 compression ratio and specified premium.
High-performance engines, such as those in some sports cars or older, heavier automobiles, often boast much higher compression ratios. These cars--for example, Shepherd's Subaru WRX--require premium gasoline and will definitely knock without it.