Hi Stormseeker,
There is no doubt that the Road Angel is a superb bit of kit, I recently bought 2 one for my G60 and one for a friends Mondeo ST24.
Both units gave false alarms every time we hit 3000 rpm, We tried hard wiring the power supply and various other things which Blackspot (the manufacturers) recommended but to no avail.
The problem it turned out was NOT the Road Angel but the cars electrical systems.
which were putting out spurious electrical signals which the road angels Radar detector picked up and triggered the units to beep as though you were passing a mobile radar unit.
The reason I am telling you this is that neither car had any problems which we new about, However the electrical problem meant that the units were unusable due to continuous false alarms. The shop we purchased from refused to take the units back, It took 3 months of arguing, phone calls and letters to twist their arms and get a refund.
Synopsis: Road Angel is a fantastic device, However before buying check the returns policy just in case!