Its definately is.
I just had mine done and there is rust on the neck of the join so a tiny bit of air passes by the gasket and ruins it.
We used lots of exhaust gunk to stop this and all seems to be good now.
Make sure yours isnt the same otherwise the gasket wont last long.
its around 7 pounds from Nissan.
Id get the nuts too if possible and the bolts are part of the backbox!!
Good luck, hope this helps