Cheers for the feedback all...
Just for info, in the hope I just have a bad tranny and this isn't a case of "they are all like that"
Mark: The range on the 413 is no better than the 411, when just 10 meters away both loose contact.
Paul: The coax is perfect, its basically brand new and I'm pretty careful not to snag them or even go round tight corners.
Allan: Its as far as it can come out of the shell on the 413
Xracer: Its on a steel chassis car, housed within a plastic case and the aerial is full extended vertically.
I ran my old Uni3/409 today outdoor's and had no issues at all, so at a bit of a loss why the new model would perform worse?