Here's one I haven't seen or read about yet. At a shop today doing Grand Opening dyno pulls (3) for a cheap price. One '16 stock Challenger A8 Scat Pack 392 pulled around 420 HP at the wheels. This is pretty much what the posted stock number is for a 485 HP car. Two identical stock '16 R/T M6 392's each pulled 320 HP! What the heck? All pulls done on the same Mustang dyno. just minutes apart. How could an M6 and A8 be a 100 HP difference? Those R/T guys left pretty bummed.