Frank To be honest I did not test it without trimming. I believe the rest needs trimming to preform best, but becuase you asked I will find an untrimed bisquit and and shoot some to see. I susspect probably a couple of feet per second more than without trimming, but I won't know for shure until I try it out.
Thanks Chris. The reason I ask is because the local shop usually uses a figure of 6-8 fps in loss of speed for an untrimmed biscuit and straight 4 inch vanes. I want to make sure that number is still accurate.