most spinners are adaptors. so. with an IS300 having relative small dish wheels it will for sure stick out.
Saw an IS300 with spinner before.. it did stick out. Look is not very pleasing.
With that kind of cash for spinners. I rather have some Volks.
an issue to consider is that the rotational mass for the spinner will make your ride rougher. The physic of it is that the mass will affect suspension in its ability to react to bumps. but who am I to talk.. I have Tein HA.
Best leave spinners for SUV or Trucks.spinner looks better on 20"+ anyways. IMHO..