Mk4 heated (all working using a Corrado VR6 loom and relays), side airbag (not wired up), Recaros, half leather/half Mk3 Anniversary fabric (trimmed by MJ Interiors).
Rear headrests added (also MJ Interiors).
Mk4 Anniversary 6 speed gearknob on a Mk3 gaitor - to match the VW motorsport 6 speed gearbox!
Mk4 Anniversary pedal covers.
Shift lights in the Mk3 16v Anniversary instrument cluster.
Red front mats from a Mk4 Cabrio red Colour Concept.
Lupo GTI steering wheel and airbag (3 spoke, with red stitching).
Hmm..I think that's it for the interior.