Bah. If they really didn't want anyone to know they did it, you wouldn't have seen them do it, James.
They swapped out their ratty old stock carb for a nice new performance carb. Neat trick, eh? Ultimately, it probably put them on par with all of the fuel-injected cars out there, giving them decent power and reliability. It was "cheating", but I don't really fault them for it.
I absolutely loved how that car looked when they rolled it off the trailer. Looked like it was fresh out from under a tree in someone's back yard where it had been for 3-5 years. The guys new how to play the game.