I find it useful to trim back the wooly silencers when I’m close to being in tune, but the bare shaft is showing a little stiffer than I would like. Alternatively, I could move the silencers further towards the ends of the limbs, but wooly silencers are difficult to move once they start to fluff out. I have to assume that if trimming them back weakens the bare shaft, there must be some increase in velocity, but I haven't measured it. About the same effect as drawing the bow about 1/2” more.