i have a black 03 spec v. no pictures and the motors awaiting a rebuild since it shat on me. which one do u have? i have a couple things done to it not much though

Mine is a GXE (1.8L version) There are alot of known problems with the spec v's. I hope on your new engine your not using the stock header as the pre cat will destroy the engine (as what probably happened to your last engine) Or the butterfly screws in the intake manifold (need lock tight).

read here if you haven't already.
QR25DE Precat and Butterfly Screw FAQ - B15sentra.net - Nissan Sentra Forum

Other then the engine, your car is completely the same as mine. I run 1 10" Type-R and its all the bass I need. Then again my music is almost all mid bass (metal/rock). My friend has 2 12" type r's in his spec and it goes really loud. A 15" is not necessary IMO.
Best tip I can give is ditch the rear speakers completely and get the best 6.5" Component set you can(Morel Ovations is what I use) Also, lots of sound deadener in the front doors to bring the mid bass to life.

What mods have you done to your spec?

ya im aware about the problems with the spec definatly gonna do everything right away when i get my motor. i just have an intake short shifter motor mounts and tein basic coilovers. i have an safc2 but im waiting for a couple things before i put it on. i have an onderground lip but i might sell it im not sure. still dont know if i want to boost the car or not, forged internals are expensive