I have been in my friend Aux's 240z that has the Illuminas---yes, you CAN tell the difference between the settings. The top setting is way too stiff as mentioned earlier, but if it fits your car for racing, so be it. The lower settings feel fine for the street. I have non adjustable Tokikos on my Z, but if I were to do it again, I'd go with the Illuminas. Just my $02.
Davy