Pro Stock. The good old days
some would call it cheating, some (like me) consider it "creative engineering". Right from the head of Chryslers racing program in a speech at the Carlisle Mopar event (2016?)..... Chryslers internal racing motto for ALL their programs (early 60's to 2000) was..."Win if you can, loose if you must, but always, always cheat". He went on to explain Chrsyler expected their racing teams to always be pushing the envelope. His point was that not allowing "creative engineering" stifled creativity.
I used to love going in Daytona and checking out the tables of "creative engineering" on full display in the garage area. One year I was there, they has several complete roofs cut off of Roush cars. Apparently the Roush engineers discovered if they moved the roof flaps slightly ahead, the driver could push up on them slightly causing the air not catch the rear spoiler. There was probable 5 or 6 tables full of all kinds of stuff just from that race. I believe Dick Beatty was no longer in charge of tech, the new sheriff was Gary Nelson who I think must have been Smoky Yunicks illegitimate son. :)