Cut an 85mm (3 3/8") hole in the panel and allow a clearance of 70mm (2 3/4”) behind the panel to fit the gauge. Put the gauge in the hole. Using M4 nut and C type bracket to seal up the gauge.
For the GPS antenna, you should securely fasten it in the flat position, black side upwards, preferably outside (or inside front windscreen) so that it has a clear view of the sky to pick up satellite signal. Connect the antenna cable to socket in the back of the gauge. And do not cut cable.