"Don't think so! Guess there's only one way to find out!" Goku immediately flies in Jacob's direction, using his powers to double his strength and surround himself with a telltale red glow.

"Hey, rock guy!" ...Stealth is not a concept that Goku grasps easily. (plus, he finds it unfair if he just punches someone before they're aware that they're in a fight) Since he can't use ki blasts, he'll just go with a good old-fashioned punch to the face. He's not sure how much this guy can take, so he'll start with small boosts and work his way up - no point in exhausting himself if it turns out that there's more to this.