Only the 340 manifolds are 2 1/4" all the others (273, 318) are only 1 5/8". Even the '70s 340 passenger is only 1 7/8". There are also some newer 318, 360 manifolds that are 1 7/8", then there are the newer 360 magnum manifolds some of which are 2 3/16". So the demand for the larger pipes for 340 manifolds isn't a big as you would think???
