The SR20 Forum has one of the most comprehensive suspension faqs around. Lovely stuff! Everything you wanted to know about modding the N16's suspension is listed in the faq. The link to the faq can be found here!
In case you need a rehash the USDM (US Domestic Market) B15 chassis code Sentra is practically the same as our N16.
If you want to mod your N16's suspension and don't know where and how to begin do yourself a favour and spend some time to properly read, understand and digest the faq. If you have questions you can always ask me and I'll try to answer to the best of my ability. Now where can I find someone to bend my rear beam in Bolehland?