yeah, Ash is right, for our cars, mods done properly will definitely add value, but obviously not at a 1:1 ratio of what you paid
you could probably work out a very rough idea of $ spent on mods vs value added to car, like say 30% or something like that. I sold my GT-T last year for low 30's, compared with say high teen's for a basic manual GT-T - so done properly with quality mods, should definitely add value
A nice V-Spec II, low kms - fairly stock, low $60K's sounds about right - nicely basic modded one for around mid-high $60K's i'd say.