well when I had a manifold gasket leak it would make a ticking noise like a bad alarm clock haha because obviously the one cylinder was only making noise every time it fired so I assume it would be the same way for a head gasket leak of this nature as the cylinder will either only make noise during firing or make a different noise for each stroke of the piston. but that is weird the cap and super charger base are covered in soot mine is all covered in soot as well but so is the rest of my engine bay haha. maybe you have a leak at the super charger to LIM that would make sense if it was a constant hissing sound then again title of the post is dosent make sense so idk