I have just attempted to fit one to a small block engine fitted with a Casa top end and it is not going well. Loosely fitting the three separate parts together results in the down pipe cocked at an angle at the manifold that I doubt would clamp down in a month of Sunday’s and the exhaust body front hanger isn’t going anywhere near home on the studs. When I’ve put a straight edge length ways across the manifold mouth it stands off by about 1 - 1.5mm on one side. This isn’t an uneven surface that could be flattened out on taped down wet-and-dry, it looks bent. When I fit the exhaust body on its own so it sits home on the studs it is right against the cylinder head (no cowl fitted yet either).
The tail can fits perfect

If others have had problems I don’t mind getting the hammers and dremel out but at £300 I would have expected better on a standard layout engine.
If others had these exhaust fit ‘like a glove’ out of the bag I will take it back.
Cheers
Tony