The only statistics we can really draw on are the ones from the games, so the true attributes of the predalien are unknown. But a rough estimate would be about 9-10 ft tall, over 400lbs at least, 60-80% increase in physical strength, mandible jaws powerful enough to crush a victim's skull, combined with an inner jaw. Speed-wise I am not sure, in the games it was roughly a 25% decrease in running speed, but for all we know predaliens could turn out to run much faster than their drone counterparts. Also, powerful rear legs, meaning that predaliens can leap massive distances, far greater than the standard alien.