Its no where near enough to have noticable effect on performance. Nova went from a round back plate to one where they took away 2 areas to to give better flow to the transfer channels. This reduced case volume, Did it have any adverse affect no. They have since gone back to round back plates as well. If you look at some of the modders that carve the inside of these motors away ie piston skirts,windows in bottom of liners, ports bevelled, teardrops on ports, liner thickness reduced below ports, crankshaft bore increased, crank port inlet knife edged, crank turbo flutes, crank material taken away to rebalance, and motor still works well if not better as you hope it would having had these mods done by a good modder. Their obviously is a point that you can go to far re case volume but just no silicon ramp is not going to effect motor performance that much. Regards Martin.