I don't think that statement is true and I don't agree. Unless you have a smaller SC pulley other than the stock 3.8" for higher boost you typically run the stock heat range spark plugs and brand of your choice based on your experiences since everyone gets different results. The only way to know for sure if you have any knock retard (KR) is to run a scan with a scan gauge capable of reading out KR or a program like Autotap running on laptop computer. It is true many of us with SC mods run Autolite spark plugs but the colder copper core race type plugs and not the regular Autolite AP (Platinum) or APP (Double Platinum). Other reasons are cost and easy to remember numbering system.
No comment on Bosch spark plugs.
