I just got a scantool, and I'm planning to screw around with intakes. Please elaborate on this...

Thanks.

Your scantool should have a flow rate value for the maf sensor. This will tell you how much air is coming into the engine. You'll need to record/log this and rpm at WOT.
For consistency, do pulls in the same gear, make sure your air intake temps, engine operating temps, etc. are in the same range and test one right after the other so the humidity is the same.
If you plot the maf flow rate vs time for both setups you can not only see which intake has higher peak flow but also which has more area under the curve.
You may just want to concentrate on the area 3k or so and above since you only below that rpm once in a race.
Note that different types of filters as well as how clean they are will effect the results.

95naSTA,

Thanks for the info. I did some web searching myself after posting my question, and I think I've got a handle on calculating volumetric efficiencies now.

I intend to compare VE'* (5 reps under each test condition) at WOT at about 4000 rpm on my otherwise nearly stock 98 LeSabre with:

You should really do it over an rpm range.
If you could, would you try just gutting the front part of the air box and then try fully gutting it? I've always wondered if keeping the rear part in smoothed it out enough to benefit flow.

Funny you should say that...I have the same exact idea. I soon will have two airboxes, and can mix and match halves as I wish. I will be testing that.