I've always used them as is, but I've probably not used all the notes, so one or more tubes may sound to be be slightly "off". Physical chime sets are notorious for this. Certain notes may be perceived to be out of tune more than others. Same goes for orchestra bells.
However, any given note itself is often characterized as "out of tune" by those with sensitive hearing and a refined sense of pitch. That's because the physics of a struck, suspended metal rod or tube creates overtones, sometimes with very prominent energy, that are outside the "normal" overtone series, i.e., the resonating metal tube actually sounds out of tune with itself. Yet, this is exactly what gives the chimes their particular color.
So, rest your ears and perhaps bring the chimes down in the mix?