I have just changed my X5 from a 4.4i to and 4.6is (low mileage late car) and I notice more valve noise from the engine at ilde (more mechanical noise) and the right side exhaust sounds erratic compared to the left side. sounds a little like it misses a beat, idle is smooth however.

Just need to know if this is normal (my 4.4i was so smooth and quiet) or if not what could be the issue?

Any help appreciated, Geoff