I experimented with this a while back on a Thunder Tiger .46 PRO (close enough to an OS .46). What my very limited work showed what that it depends on the RPM you're turning as to whether or not it will help. More flow is not necessarily a good thing since flow through an engine is all about pressure pulses. Changing the flow changes the timing of the pulses, so a more open passageway can actually restrict flow. What I found was that with a prop that gave me 13300 rpm peaked on the ground removing the baffle actually cost me 300 rpm. Given the greater noise it was a lose/lose. I didn't notice any difference in needle valve sensitivity although the settings did change. When I went down to less prop I got 14200 with the baffle in and 15000 even with it out. It makes sense that the manufacturers put the baffles in given that, since most sport pilots run their engines around 13k-14k rpm. It actually improves the power there, and it leaves the option to remove it for the pattern pilots and racers who want to let their engines unwind more.