in my old vn i used the standard diff with a kaaz 2 way lsd center. probably a bit of an overkill but i was sick of killing standard factory lsd,s. plus i knew that it would be able to take a lot of punishment and hold up well.
thats what i did. imo the standard diff aren't to bad. plus i wasn't chasing mega hp so a 9" would be an overkill and they are heavier. the kaaz brand new fitted with 3.46 gears installed ready to go was $2800 roughly from memory purchased about 2yrs ago
if its to be driven on the street frequently then i wouldn't go a mini spool but if its only to see the street every now and then with the cars main aim for show then a mini spool could be a good choice