I've got one because it's the only internally gated DP that I could find at the time that would clear my Kenne Bell (same as ATR) Headers.
Mine is installed on the car & never measured it. I did look at it before installation and didn't seem any different than the puck size on my old THDP that I removed.
That being said, it is most likely the same diameter as the puck on SE Turbos' standard radius bend (Non ATR) down pipe. Bought mine about 4 years ago, so......unless they've changed the puck size since then?
I will be porting the wastegate hole on my new DBB 5857 SP over the winter....so I can measure it then & let you know for sure.