If that's what the FSDO says I won't argue! To me all parts on
aircraft are "certified" as are all installations. However, if they
take "certified" as extream as to mean part of the original type
certificate then I'll go along with it. However, I think technically,
all STCs are technically considered modifications to the individual
type certificate. Many (including this) even require updates to the
POH. Certainly such as system would include emergency procedures
addendum to the POH.

-Robert