I'm having a disagreement online. My memory is I believe David Pearson in a Ford/Mercury for one race in late 60's? reconfigured his exhaust to exit the rear center of the car. It made it difficult for other cars to draft him in the race due to overheating. David ran very well and was always in contention or won the race.
Nascar never allowed it again.
The disagreement is whether it was banned do to overheating or carbon monoxide, which I don't dismiss, but that is not what the competitors were complaining about at the time post race if I remember correctly.
Anybody remembers anything about this topic, who what where, why?
Goggle is drawing a blank.