Not sure if anyone has considered this. I was on an acura forum and it struck me that all of their honda motors are designated by a certain letter. K20 is the rsx motor....etc....All of the blocks within a certain engine designation are the same and therefore would all swap with the same relative ease. Meaning that it won't necessarily be easier or harder to swap a B18 (integra) rather than a b16(civic SI). Having said that, since we know that it is possible to swap a k20, it occured to me that it would also be possible to swap a k24. k24 are the TSX motors. The rsx-s motor has 200hp (7400rpm) and 142lbs of torque (6000rpm). The k24 TSX motor also has 200 hp (6800 rpm) but has 166lbs of torque at 4500 rpm. The reason these two motors have the same hp is because the rsx-s has v-tec, while the TSX motor has none. Therefore, it should be possible (i've searched and it has been done) to take a k24 engine from a TSX, put on a k20a(2) cylinder head with v-tec, and put that in an elise. The result would be 2.4 liters and over 200hp to the wheels, and just as easily modifiable as the k20, with a lot more potential because of the 20% increase in displacement.