I would recommend you do a search of the site and look around on Sentra.net and NissanPerformanceMag.com for more information about body kits. Check out the Member's Rides section just below, find a kit you like, and then ask about it. Your more likely to get the desired response .
However, to answer your question, my two favorites are the Stillen GTR kit and the VIS Omega.
yeah i ordered my gtr bumper from nopi but i got no response from them for a couple days and then i called and they said they did not have it in stock nor did they know when they would have it, same for the momo hub. just a warning...call nopi first. i had to wait an extra 8 days to order my bumper from erebuni directly and almost missed out on the last on they had from the last shipment. but it's alot more expensive from erebuni....just the bumper was $440 with shipping. if you like the omega, liuspeed can get it for you for a really good price.