The throttle bodies are mounted by applying silicone gasket to the inlet manifold and then bolting the manifold to the engine head. The first attempt went well, then I thought I'd double check behind the butterfly valves only to find some of the gasket had squeezed into the airways - this would not help the engine run its best, so the whole lot had to come off, the silicon clean off, new silicon applied and the assembly remounted. This also included removing the alternator and refitting. What a pain. Fingers crossed it is all okay now.