Oh yeah, I forgot about the huge temp difference.
Not to be picking nits, but the ram air is more effective when the entrance is tapered, as in -if you've got a decent funnel to cut, go for it!
If you've got a spare vacuum gauge laying around, you can put a barb fitting in the intake pipe after the filter to get a good reading on pressure change at a specific throttle setting with each type of intake.
In theory, the HAI, then the R-HAI, then the CAI, then the R-CAI should have the least pressure, respectively.