Wow, there aren't many Signatures out there, to the best of my knowledge they were renamed to the "Limited" shortly after ParaOrdinance decided to offer the public a more competition ready or factory customized pistol.
How long have you had your Signature P16?
Others might be able to help you with the regulations and rules of the type of competition you want to shoot or the class you want to shoot. I'm just interested in the pistol, I've got a P14 Limited and at the time I decided I wanted one they were known as the "Signature" but it didn't last long.