Managed to change the splash screen ok and checked to make sure it had changed by going into nav tweak and checking.
Burnt disc at 8x in Nero (lowest) still wont read it,saying incorrect cd/dvd in....

One thing I noticed , if I go into (my computer) on the pc it is reporting the original as (nav) when the burrt disc goes in it reports it as (my disc),probably a Nero thing.

Nearly there,any tips guy's?

Update...used a slightly different method, opened the original v28 (img file) in power iso,changed the splash screen and burnt the disc all within the one program.It updated the s/w back from v27 so all seems fine.Brought the disc back up to the pc and opened it up using nav tweak and it has changed the splash screen on the disc so it should be on the car also.

Thing is, the car has lost its gps signal,will come back on when i pull out of the garage and it boots up correctly,need sleep...zzzzzzzzzzzzzzzzzzzzz