Davepir:

You take off the STS and lose 17 fps? That seems like a whole lot of speed loss for an accessory like that.[:-]

As far as IBO, I have 3 bows with 29.5" draw and 60# draw weight.

The one rated 310 IBO shoots a 315 gr. arrow at 298 and a 395 gr. at 270 fps.

The one rated 316 IBO shoots the 315 gr. at 307 and the 395 gr. at 279 fps.

The one rated 330+ (not sure of the exact rating, it is a 2001 bow) shoots

315 gr. arrow at 319 and the 395 gr. arrow at 286 fps.

All of these are with a D loop and catwhiskers or string leeches only. No peep in the string.