Slightly more redneck approach, how bout you restrict air at the filter, instead of the throttle plates? Quick testing would be duct tape over part of it, then cutting a metal strip as a more use-able/easily removable primary killer, then trim the timing in your EFI table to fine tune. Basic example (numbers are made up), say you have a 3" tall, 14" dia. round filter. Tape off half of the circumference and see how much ET you kill...add or remove tape to get you in the ball park of where you want to be. Then cut a strip of sheet metal/aluminum/SS/unobtaneum/whatever to the height and length of tape you found that worked. Then like I said, pull timing to get the last few hundredths you need...as @SLOPAR72 mentioned you'll need lots of data to get the timing dialed in relative to weather. Then, when you're running your normal brackets you can pull the filter restriction and reload your primary tune. Maybe simply dropping filter height will restrict enough, or getting a restrictive paper type filter? Dunno...just throwing some ideas out.
