Interesting to know the NHRA guidelines...................but I base my estimates off of real world numbers from my cars and people that I know which have the slips to prove it. There are soooo many factors and different cars and configurations that there's no ONE rule to cover all 100%. The easiest way to prove what I mean is to run your car(s) wherever you guys(at or near sea level) live..............then make a road trip out here to wonderful Las Vegas and do a couple passes to see how much slower you will run.