The Check engine Light will come on if there is any modification on the engine. Its not a question of quality, its the question of how the on board computer was programmed.
On the VX model, as there is no power steering or a/c, the engine computer has been tuned to a certain load and performance index. As you modify, the performance index changes and since the load on the engine increases, the on board computer does not recognize that load and the light comes on.
On the question of a/c compressor. These compressors have ratings at different rpm. If the rpm is high, the compressor might perform but it will decrease its age if it rated at a lower rpm.
