As promised, here are some pics when I swapped the mids out.
Always make sure that you purchase a new set of bolts, nuts and gaskets just in case
Removing the mids is easy. A total of 7 bolts/nuts and that is it. 2 are 17/19mm rear, torx socket for the middle hanger and 12mm for the DP bolts. make sure you use a decent breaker bar cause they will be hard to remove.
Also, even though on the pics the N55's look longer than the N54 mids, they fit with no issues
Final result
They are lighter than the N54 mids
Also, a look inside one of the cats.......how does exhaust go through there??