Excellant point Tom. Let me interject with my swapped motor experience. My alternate motor accomplishes two things, it gets me a better intake manifold that didn't come with the generation of motors in the Z3. Also, I get a smaller motor so we don't have to weigh over 3k lbs. My alternate motor has the same bosses and transmission as my current motor, so it sits in exactly the same spot as the stock motor, bolted to the original ZF transmission when that motor came with a weaker Getrag from the factory. If I were to swap in a four cylinder, I'd place the motor in the exact same spot the four cylinder motors sat in the four cylinder version, and it too could be bolted to a ZF transmission.