I think the JDM engines have higher compression, but I could be wrong.
On a 96 SE-R you'll gain maybe 14hp with the S3 cams and like 16 or 17hp with the S4's. Check SE-R.net for the real numbers, these are just numbers off the top of my head.
91-92 intake cams would give you 4-6hp. If you've never done mechanical work on your car don't attempt the cam install yourself, they may be too involved.
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Jordan White (Stormy)
'98 Sentra SE(R)
Hotshot G3 Header, Hotshot CAI, JWT s4 Cams, KYB AGXs, Eibach Sportlines, Courtesy F&R STB's, ES Mounts, MOMO Shifter, Nis-Knacks chrome projector headlights and clear corners, 205/50/15 Pirelli P700Z's on SE-R wheels, 205/40/17 Kuhmos on 17" Borbet Type S's for the summer
15.1 @ 90mph at Englishtown, NJ - 14's oh so close