RE: How can this be ?
Actually the main thing that gets overlooked by most with speed potential is the amount of reflex a bow has.Yes cam design also plays a big factor.
How do you think we are seing such high speeds out of the parallel limb bows with close to 8" of brace?Look at these bows and you will see most have around 2 1/2" of reflex(and ratical cams).IMO this will also eat up some of the forgiveness that you gained from the brace heigth.Really it will most likely balance out in the end.
Now,is it possible that the Havoc is faster?Yes, but you don' t know all the variables.Was the draw length measured to be exact on both bows?Was poundage set to be the same with the same scale?Was the arrow tuned for BOTH bows or just one of them?
I take most of these comparisons with a grain of salt.