I have no idea how to compute power at different altitudes and my WAG is that different props and engines would make any comparison inexact at best.  Ed probably would know best.
The best way that I know of to determine if you need this is to look at your MP on the EM-2 at a steady RPM and see if it varies.  Mine varied plus or minus 1 and a half tenths.  If it varies with the engine OFF, you have a EC-map sensor problem.
I went to Home Depot and got a Zoom oiler  from the Swamp cooler department or where they sell oil for those of you who are lucky enough to live in hot humid places. Probably next to the WD-40.  It has a small  plastic cap and a spout that pulls out Several inches.  I cut it off and inserted about 2 inches of it into the vacuum line going to the map sensor on the EC-2 then locked it in place using several nylon wire ties. It's about 1/16th inch ID, I never measured it.   Greatly improved things, on the display and I got more RPMs.  Then I made 2 accumulators using 2 inches of 1/2 ID tubing, rolled up green scubby pad tightly and inserted it into the tubing.  Went to the hardware store and got  4, 1/8th inch barbed  fittings (brass) x 1/4 MPT and inserted it into both sides of the tubing, hose clamp it tight and inserted it into the vacuum line.  Don't remember if before or after the restriction.  Even better now.  Works great!  Try it! Experiment!  I love these cheap, quick hardware store fixes!

Don Walker
Flying N113BR