Last time I got see what difference between FD and FDR in a magazine in kinokuniya. It's in Japanese. But lots of pictures that highlights differences. I remember the engine has polished intakes from factory. All the suspension is different. The control arms are also different. Running different camber also. The chassis has different reinforcement all round.

Yes. So the things that cannot upgrade is chassis. I suspect the front lower assembly also different and not pnp.