Ok, I don't wanna sound like an idiot for asking this but I figure I'd ask just so I know for future reference. I'm mostly into old cars, as in pre-'63, but can someone explain to me when everyone talks about how they are at a Stage 2 upgrade or Stage 4? I know it has to do w/ adding new stuff to your car to make it perform better but I'm just sorta confused a bit. Just a basic explanation is needed. Thanks guys.