I'm no engineer, but the issue with drag racing is that downforce is a bigger concern than a low Cd. It's not like a salt flat car, for which acceleration can be quite leisurely while running on a dry lake with zero obstacles. A dragster, on the other hand, is all about traction, and making sure you don't hit the other car, or barriers.
If anything, adding a kammback and wheel skirts wold just be added weight in this case.
Of course, if anyone here actually is current on their pro-street drag racing, feel free to correct me.
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