HP Correction is a good way to compare runs to one another. Its based off current weather conditions against ideal weather conditions. The generally accepted standard being 0 elevation, 59 degrees, 0 percent relative humidity and barometer of 29.92. Many factors change how a racecar will perform for sure. Barometer and vapor pressure, grains of water seems to be the biggest. Obviously altitude plays a role but as you go up in altitude the barometer drops, generally 1.1" per 1000'. So its a very good baseline to compare one run to another. For instance in places like Vegas 1.12-1.15 is a typical HP Corr number. I have seen it as low as 1.09 around the Thanksgiving race and as high as 1.17 in August during the day. Which is mainly altitude and temp related as humidity is generally fairly low. I have never had the chace to run in .999 air or lower but we have come close in the Vette at Norwalk at 1.01. I hear that some of those east coast tracks in the fall see .990 HP Corr days

I have never seen Performance Corrected altitude number. Would be curious what numbers they are using to calculate that and see if the claim is correct. In my experience when it comes to prediction baro, VP and GOW are the biggest contributing factors for my stuff anyway. Outside of track conditions which in some places can be a huge part of it. Also have foudn being on the fat side seems to help repeatability as well.

Very interested to see how your next outings go with the hood/scoop/air cleaner testing. Have you ever considered going to a 16" wheel?