Search this forum for direct and port injectors. IS350 have both whereas IS300 has direct injectors only.

EDIT: I could be wrong if both engines are in fact 2GR-FSE. In that case, my sincere apologies. That would mean that since 2015 both IS300 and IS350 use de-facto the same engine hardware including injectors.

 

I believe you're mixing the IS250 and IS300 engines up. The IS250 doesn't have port injectors. AFAIK, the IS300 has the same engine code as the IS350 so it should be pretty much the same engine hardware.

 

Yes, both the IS300 and IS350 use the 2GR-FSE, with the D-4S injection system (port plus direct).