I am not convinced that this bike is post 1978. The decal could have been added later. The decals on the frame tell me it could easily be a 73-1976 edition. Also, take a look at the brazed on cable guides typical of that era.
Those are authentic decals, the colors may look odd or bright, but those are Screen hand printed decals, original from Benotto. I have 2 sets of those and depending in how you took the picture and under what type of light, they will change colors.
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