I actually considered both as well but eventually went with ones from
SLP instead. Even the painter that did my spoiler did a double take when he saw them. He first thought that I had cut the actual gills but got a little closer and thought they were airbrushed then he got real close and realized they were just stickers...
Here's a shot of someone else's Camaro in IOM...
EDIT: Not trying to push you away from RiderGraphix or BigWorm, just thought I'd point out another option. I've dealt with both of them (hood spears/bowties from RiderGraphix & bowties from BigWorm) and had no problems with either one's products or quality.