| UK version of the Opel Manta A series exhaust |
The downpipes have to merge much closer to the exhaust manifold than on a European car, in order to clear; the steering column, clutch cable and brake servo. Whether or not this restricts the flow and reduces horsepower is a moot point.
To complicate matters further, automatic variants of the Opel Manta A series require a couple of extra kinks in the downpipe in order to clear the much bulkier gearbox. I have even heard that on the last of the Opel Manta A series, produced from August 1974 onwards, had a different design of engine mount, moving the engine slightly further forward and requiring a marginally longer front pipe.


