Welcome to the Sprint club.
More info and pics needed... (Colour, km traveled, options etc)
Have a look at this thread that I started recently.
ED XR8 Sprint Spotters guide
I also have a vibration at the same sort of RPM as you but have not spent much time looking for it..
Is yours a manual or Auto???
If you want to get some more info re the car. You can contact FPV and they will have a look in the system and see what options it left the factory with etc.