"High Cluster" means a "Big Bordcomputer".

No Bordcomputer = Nothing
Low Cluster = temp. / speed / consumtion / range
High Cluster = (as low cluster) and: Time 1 / Time 2 / consumtion 2 / time / date / distance / timer / arrival timer ...

If the Nav was build in by bmw you should have the high cluster of corse. but if it was a retrofit, perhaps you have to change the ike, too if you just own a low cluster.