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A car has hard points for mounting the engine. I can replace the soft stock bushings and put in harder ones to reduce engine movement.
OR I can also put a little gas cylinder at the top of the engine and transfer all that force to my shock tower. Sounds good for when I'm powering out of a turn. Or I can put the force onto a weak part of my body. Meanwhile, the other side will attach to the engine's head. That way I can put lots of sideways torque on the cylinder head because, you know, that's good for everything.
On a boxer, things are even weirder. Now you're talking about an engine that lifts one side and pushes down on the other, as opposed to one that tilts to the side. You then have to put the stupid thing pointing upwards on one side of the engine. Where it would attach to then? Some fancy brace into the strut tower? Yay, upward motion on your strut tower every time you accelerate. No problem there, right? Oh, but it gets better. That twisting force then concentrates on the other side of the engine. Physics, you know. So now you're compressing more force onto the opposite engine mount. I wonder if the mount will like that?
People will buy anything. My favorite has always been the grounding kits. A hundred+ bucks for some wires. Oil additives that do nothing. Spark plugs with fancy looking tips improperly gapped for the car. Tiny, weak fans for the intake that actually reduce air going into the engine. HID bulbs in stock housings that blind oncoming drivers. It's all pretty funny.