I had misfires and pulled error code 21 from my N/A R34, so I got a set of Splitfires and a mate came round to help me install them. When we put it all back together and gave it a crank, the engine ran very rough, it was honestly much worse after swapping the coils than before, completely undriveable. There was a loud popping noise coming from the intake manifold, a strong smell of fuel and smoke from the exhaust and after I moved the car back into the garage I noticed that there was a puddle of coolant underneath where the car had been parked.
My mate reckoned the intake gasket was cooked, which made sense because when we opened up the intake manifold earlier in the day the gasket looked out of shape and it was difficult to fix the manifold back in place since the gasket wouldn't line up and one of the nails was threaded.