Helllllll yessss it is.
Of course, at auto-x speeds you won't notice anything. In fact, I prefer being wingless for autocross, as a reduction in rear end weight helps induce a little bit of oversteer improving cornering.
At speeds seen on track days, the wing (or lack thereof) is definitely noticeable. If I pound an on-ramp (in Mexico of course) at 80-100 mph, I have to be more careful about lifting suddenly. :lol: