Thanks for the feedback. I don't know these fine points about the K series or any Honda motors really. I didn't know that just swapping the head would reap most of the benefits of the K20a2 either. That's really impressive. What I want from the RSX-S drivetrain is the higher horsepower and torque output, higher redline, and 6 speed transmission. Would I need more than just the head (ecu, etc.) and would that have an affect on the redline?

The main point is for both cars to get new engines at the cost of one.