The decat has a three bolt fitting on the system end because it was made up to fit on my Cav. However it lost a bucket load of low-down torque so I removed it.
When It was fitted to the Astra it had the same two bolt fixing that you have and with the TBs made a lovely differnece the the power output and torque was up.
I would just get the three bolt fixing removed and get one of the two bolt flanges from the other two decats welded back on.
Obviously this would be better done with it all fitted to the car.
I'm glad it reached you okay.