1965 Dodge Dart 270 2 dr sedan

I'll help you here...Day 1 you buy the car new,off the dealer ship floor(60's -70's musclecar era)... Day 2 :minor modifications,begin( Tach's,after market wheels & tires,headers and exhaust..),the more serious would add intakes bigger cams,deeper gears & shifters.The hard core race car people : Disassemble the long block,bump compression,bigger cam,sometimes port the heads,bigger race intake,extra stout pressure clutch, extra deep gears...
So what you're saying is that a Day 2 modified car can be modified to any level you describe, the term means that the car was modified when brand new?
I'm only asking because I know the engine is pretty hopped up already.