I'm sure you could make something like SHOT work with transfer port injection. You'd have to turn the motor somewhere between 2/3 and a full rotation to push air past the injector and get enough compression going for it to ignite the mixture, and that would mean pushing the other piston through a full compression stroke. I suspect SHOT only has to turn the engine around 1/3 of a rotation, and direct injection probably makes it easier to get a combustible mixture and pop the motor into life. I know it uses a capacitor, and the flywheel/stator setup acts as the starter motor, but it's probably pretty inefficient. I wouldn't be surprised if the amount of power required to turn a TPI motor enough to fire it makes the system less practical and desirable - maybe moving close enough to e-start that it's not worth it...