The northcreeks will improve the sound considerably, but still no match for the Nautilus. Actually, I thought the 801s were not as good sounding as the 802 III. Because of the large bass driver and the small 5" midrange, it wasn't the best result.
In short, no, they won't compare and certainly won't exceed the Nautilus 801.
In short, no, they won't compare and certainly won't exceed the Nautilus 801.