I recently fitted V force reeds which came with a qtr inch spacer and fitted that to space the reeds out from the cylinder, the info said this was to allow a better flow into the upper intake port? , but they have made a huge difference to the bike. Compared to Boyesens they are night and day. I don't know if the spacer added any power to the bottom and midrange, but the whole package really makes a bigger smoother hit.