Fcuksticks.Clam off tonight, it isn't the manifold but the down pipe.

What downpipe did you have fitted?
Update from Chez Techie
Front clam off. But stainless fixings are no good if the fcuking stupid captive bolts they fit into disintegrate or turn into a blob of rust. Coolant all in all of the moulded sections on the top face of the crashbox. I've definitely got a leak.