why dont you just buy an actual intake. that way, it doesnt woid the warrenty emissions wise since you area in cali, and you dont have to play mind games if it'll fit by the battery.
just grab the aem or injen.
250 for cai shipped, and 150 for what you are trying to create shipped.
http://www.b15sentra.net/forums/showthread.php?t=143024
this way, you dont have to argue about mods and stuff to polive if you do get pulled over, or have to explain for emissions reasons.