Yes, their
4 PORT auxiliary system is what will REALLY help this symptom of DI out (
besides the aftermarket hybrid/big turbo power/tuning benefits/necessity), as the throttle body SINGLE injector system has VERY uneven distribution to the intake valves, and not enough force to REALLY keep them gunk-free.
Could you image how hard such an uneven fuel distribution would be on the engine? I think that DHM found the limits of the 5th injector systems with a lean 3rd cylinder, but that kind of uneven distribution is an order a magnitude (at least) from having any effect on unequal value cleaning.
Also, don't the 4 port systems just spray into 1 of the 2 intake runners per cylinder? The Boomba Racing plate does. I don't think that the intake runners are connected inside the head so the 4-port AUX systems don't "clean" 1 of the 2 intake values per cylinder.
I'd guess that the benefit, if any, of the aux fuel systems with keeping the intake values clean is more by keeping the oil in suspension than by actually cleaning the values. None of these systems are cleaning the valves with fluid gasoline or with any more or less "force."
That said, after seeing the pictures of buildup after 11,500 miles, I think that I'm ordering a catch can. [MENTION=5976]ron@whoosh[/MENTION] - incoming!!