Not as 'streetable' as far as registration and insurance goes.
They are all built out of BASE, 2 door, Euro/Brit Fiestas, with an AWD, FIA approved WRC 'kit' fabricated into them, and with built-up, ~400 HP 1.6 engines, and sequential gearboxes, of course.
So
even if (as I've suggested in the past) it would actually be less coin to buy one of these in R5 guise instead of trying to fab up/engineer functional subframes, etc., and then try to 'reverse engineer' it to get it to be 'street legal' (IF that is even possible?), you still have the VIN plate number problem as far as domestic use (registration/insurance) goes.