Under heavy load the car only uses the direct injectors, not the port injectors, so swapping in bigger port injectors won't do anything for you when getting on it.QUOTE]
Are you sure about this? Not trying to be picky but I remember reading the opposite. I.e. The port injectors were only used at WOT (or High RPM).
In any event, the system is complicated and it is slowing down the performance aftermarket. As a IS250 owner, I think it would be hilarious if the IS250’s became easy to hot-rod while the IS350’s weren’t due to the combination FI system. It would stop some of the 250 hating that goes on.
Just my rant.