They let the cat out of the bag years ago on the rules .Allowing 1.5 points more compression than the cars originally came with .Gearing they never came with and other things . One of the hemi's has an engine that has had unlimited founds spent on it as well as the one firebird .I know they had over 70K spent on the hemi owner has unlimited funds spent on his cars even tried several different exhaust systems at track rentals.
I had less than $2500 in my CJ when it ran 12.01 at 113.75 .It is not a max effort engine . Flat tops ( 2 new 6 used from another engine) tbird block and crank I got for $175,set of aftermarket steel rods , zero deck ,heads milled to minimums,good (BES figured )stock lift cam ,stock 735 holley with two sizes smaller than stock primary jets with stock rears ,dura spark dist,NAPA ign box and wiring from John V. Good mandrel bent 2 1/2 inch x pipe exhaust .4.11 gears shifting at 6200 rpm . Car is heater delete ,radio delete ,no p/s or power brakes . I would bet the cars faster than mine have had 5 to 10 times and some much more money spent on their engines than mine .