I was perhaps the first person to import a 4-2-1 manifold into europe, there are only 3 which I'm aware of in europe (mine and 2 on vx220's)
there has been a couple of 4-1 manifolds, but they only give @5bhp, whereas the 4-2-1 gives @10bhp
not a straight bolt-on, room has to be created for the manifold, aircon pipe needs moving + loom, downpipe needs making
but was it worth the hassle..... YES