DNA STAGE 1 is simply the fitting of an aftermarket air filter. Replaces the standard filter. DNA filters have a better flow ratethan standard AND k+n.
Stage 2 is the addition of a DNA filter that is screwed to theside of the airbox in place of the original cover.
Stage 3 is the complete removal of the standard air box and a new DNA box goes in its place..its essentially one big filter!
Make sense?