1972 4/4s came with no air filter and a lid for the carburettor. So the fitment of a K&N didn't cause jetting problems. A car that came with a paper filter, may need leaner jets if you put a K&N on it.
4/4s if you keep it slow, won't open the second choke and can do fantastic MPG. I got 45 mpg out of Woodstock on a long and slow trip.
Not what a Morgan is for though, and the engine I sold the car with did 25mpg if you utterly behaved, and about 8 competitively. Yes, 8!
