S identification

[Boxx]

Looking at mostly S's.

Some are de-badged on the trunk, so no "S" identifier.
Door rails have the "S", but they can be added simply.
Dual-exhausts, but they can be retrofitted to a 2.7.
White guages, but I've seen those on base models too.

So, aside from a few insignias, dual-exhausts and white guages,
is there anything else that will definatively indicate S,
that isn't easily modified?

Something like maybe the sixth digit on the VIN is "S" instead of "B".
Can't change that.