I know the BT1 ECU on the VR has metal surrounding where the wiring plugs into the ECU.It is usually plastic and coloured light blue on normal VR ECU's. Metal is used on BT1 ECU's because the BT1 ECU is RFI shielded to stop interference from the police radios etc.On the VS ECU where the normal ECU has two pink and one blue plug,check to see if its metal instead of pink and blue plastic.Also check the letters on the ECU itself,the VS police versions should be numbered BSTH,BSAJ or BWCS,these are RFI or police versions of the VS ECU,and yours should match one of these codes if it is a BT1 ECU..You can also check to see if the chip has been swapped,remove the two torx screws and remove the metal cover,theres a blue memcal in there that unclips at each end,just unclip it,remove it from the ECU,then remove the blue cover from the memcal and check the sticker on the chip for the code ,it should be the same code as whats on the ECU itself.Other than the RFI shielding,theres no difference between the BT1 ECU and the normal VS ECU as far as performance goes.The tune is the same as a normal VS chip.