As far as I know there shouldn't be any difference in TBs between the years.

Sorry to be controversial, but I don't see how that spacer is supposed to do anything other than restrict air-flow, as it's actually occuplying mores space than the solid "circle" of the TB - I don't see any real-world, measurable results so please post some if you have access to any - sounds like magic-fairy-dust-voodoo to me.

-- John