Martin, I thought the sigma was the plastic black top engine labelled the SE ?, this is a silver rocker cover with a small black cover over the plug leads. The sigma leads were always visible. If its the same as the sigma, then thats great. They are good engines. The haynes manual doesnt say theres a difference. They have the 1.4 as the SE version and the 1.6 as the silvertop like mine, weirdly.