Just in from almost 1.000 km (562 miles) of hilly backroads to attend the Barber Vintage Festival. The change to the Sport is delightful! I feel really lucky it worked out so well.
The *tone* reminds me of resetting the intonation and (string) action on my bass guitar - so much easier and enjoyable to ride (play) and such a nice, harmonic *ring* on the throttle. I don't think anyone else could hear the difference, but with the bell mouths right below my ears, the change in tone is just lovely.
I realize that the only "quantification" has been the change in idle speed and throttle body synchronization (and, perhaps, fuel economy - one more fill-up to gather final data), but having turned over 97,000 miles /157.000 km on this trip (while topping the ton at that moment ), my empirical impression is exceptionally positive.
I am one to say the Spine Frame airbox can be a lovely piece of kit!