Having a issue with my ignition, car was missfiring like all hell if you went to a certain rev about 4k revs. Bought a new king lead and coilpack which sorted the missfire, but its still making a massive bang if boot it and it reaches certain low revs capping out about 4k again. Im running a td04 with fcd and rising rate fuel. Could this be the result of a boost leak or timing out etc. Cheers