dropping the cr depends on the cr. if you were to turbo the 4afe you would have to either chip the existing coomputer, upgrade injectors/fuel pump, lower comp ratio, and get/make manifolds. yes 4afe's are very cheap. i picked one up complete with computer, loom, sensors, coils everything to make it run, for $150 in running condition. i tested compression etc and it was peferct. so i dropped it in a ke30 for a mate!