Even with the "Supercharged" badge, I think your lower trunk lid looks too plain without an emblem.
My preference would be a bow tie but I think the modern SS like the one Sparks sells looks good as well.
If you decide on replacing your bow tie, I have to second the comments from djcfuzz regarding Lupe at River City Creations. He offers a wide variety of custom painted bow ties and his workmanship is top notch. He did the taillight bezels, bow tie and black ZL1 emblem for my car and I couldn't be happier with the way it turned out.