My bow is a 2008 Firecat - not exactly the same but quite similar with respect to cams and all. Some time ago I took it to my dealer and shot their 360 grain arrow through their chronograph and it consistently shot 290 fps with my DW at 63 lbs and DL at 29" - basically the same as what you're saying your Onza 3 is set to. Based on what your setup is shooting I'd venture to say it's a little slower than what I'd expect. Are you sure about the draw weight and draw length it's set to?
2008 Martin Firecat Pro-X (29" DL, 66# DW), home-made TRG, new VEMs, DS Advantage/HHA Pro-5519 front sight, No-Peep Sight Eliminator, Limb-Driver arrow rest, B-Stinger stabilizer/dampener, custom upper STS, G5 Head-Loc quiver on custom mounting bracket. Gold Tip Velocity XT300 arrows with Bi-Delta 2.5" Sharkstooth vanes and Grizzly single-bevel broadheads, 498 grains at 262 fps (22% FOC)