Humm, let me check.
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I looked at the wing this evening and both sides are set back about 1/8 of an inch, maybe a little less. In person it is not really that noticeable unless you are looking for it. I would not consider it a problem or a deal breaker in buying the wing. If I get a chance I'll take a closeup photo to show the setback, but it may not be readily visible in a photo.
I looked at the car once more, this time in broad daylight and the wing is flush with the tail light.