Plot out the suspension angles when the car is in motion.... Not at some 7" travel thing like a lot of these theories are working under, but the usual 1 1/2" ti 3" of travel from center, then plot in some squish and the pinion's natural tendency to climb up the ring gear...I've guessed at 1 degree with heim ends and as much as 3 degrees with poly ends on the rear arms.... All the "equal and opposite" stuff works good on paper, but for some reason I've always had the best luck just setting the top of the engine level at the intake, and somewhere between 1 1/2 to 4 degrees of pinion down.... I don't claim to have all the scientific data as to why this setup works, but it's worked for me with no driveline issues (other the too much power combined with too much bite and a few broken parts from that) on drag cars and street cars for years.... I think a lot of it is people looking at these angles in static, no load conditions and not taking into account just how much things back there move around! I think this equal and opposite thing works great, but most people don't have the application down right. Found over the years it also has a lot to do with tire flex (on acceleration and over bumps), most of this stuff (as well as suspension settings) are done in a "no load" condition, ie the car sitting on jack stands and no account is taken for the weight of the liquids carried in the car, driver and passenger weight, and a host of other things. Companies like Inland Empire do a good job, but you've also got to remember that their recommendations (much like OEM specs) are "generic" in nature, allowing for wheelbases from 95" to 115", and not necessarily ideal for a short wheelbase car with 400+ horsepower being applied by a drivetrain that actually works, not the OEM crap of eating up 20% of the power produced in parasitic loss..... Think about how much all these static changes changes by the time you're on the road with two adults, a trunk full of junk, improperly inflated tires, and 15 gallons of 92 octane. I'm not an ME, I just do what works based on trial and error over the years.

Also, I've always wondered just how much of this written stuff from the experts in whatever subject is just some guy with little or no practical experience expressing something on paper that is meant to either justify his existence or sell whatever product he is pedaling???? The one absolute I have found to be unfailing in building Hot Rods and Race Cars, is that there are no absolutes!