Marty I guess we could argue all day about the "perceived" performance gains from spacers.
Spacers have served reliably on racing engines with carbs. The spacers of various sizes are used to contain standoff and also to gain or lose velocity by changing the length of the runners in the plenum.
HOWEVER placing a spacer anywhere in a TB system might make the owner THINK he had done something, but it is all pride of ownership.
You know very well that if there was any change in the volume taken into the chamber any of our modern engines would complain loudly! Knock sensor or not the effect of the volume change would be the same.
So no change in the volume...equals no change at all!
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />