How much money do you want to invest to your suspension? There are lots others you can do. (they are all optional) You can get the rear upper mount from Motivational Engineering, Polyurethane bumpstops, Front camber plates, anti-sway bars, etc etc...
Did you read "Kojima's Garage" on Sentra.net? In case you didn't read yet, here is the link. This is very helpful.
http://www.sentra.net/tech/garage/suspension.php?
This should answer most questions you have.
Good luck