[olddog]

I know nothing about the CHI heads. I see how smaller ports would help the low end. Mid range is likely a wash, but top end the 4v should be better. If the air gap will bolt onto the 4v heads, you may want to try that combo first. Seems I read that this can be done and even though the intake ports are much smaller than the head ports that flow is not hurt. I'm not certain that I have remembered this correctly, but it may be worth looking at. The intake has much more to do with getting the low rpm velocity up for better low end torque than the heads. Since the 4v heads flow better at high rpm this may give the best over all performance, assuming this will bolt up.

Anyway what ever you find out I would be interested in hearing the results.