Sra 3000 tracer radar

I recently purchased the SRA 3000 TRACER RADAR GUN.My last gun was a bushnell and I had heard that you add 1-3 MPH for that gun.Is that the same for this gun?
Also I would just like to know what people think about this gun overall.
thanks

Personally to me if its not a stalker of jugs its a waste of money