Late this spring, I took my bow over to a shop to chronograph some arrows. I was shooting a TM Hunter when I started shooting. With 440 gr. arrows, I was getting 263 fps consistently through the chrono. I tried out one of the new GKF Whisper Disk rests, and the speed dropped to 261 with the fletching aligned with the slots as best I could. When I purposely mis-aligned the fletch with the slots, the speed fell to 258 fps. Out of curiosity, I put on an untrimmed B2 Whisker Biscuit rest. The rest had been on the bow previously, so I knew if I lined up the rest bracket with the marks I had drawn on the riser, it still should be pretty well tuned. To my surprise, when shooting the same arrows, the speed was now 263 fps. Exactly the speed I was getting with the TM Hunter, which, BTW, was carefully checked for fletch contact. If you are seeing 30 fps difference in speed, then the bow wasn't tuned properly before the drop away was installed.
