The RB25DET has a factory blow off valve thats pretty hard to miss, its on the crossover pipe that runs across the top of your engine.
Your spark plugs can be found under your coil packs, which you will see if you remove the black centre panel on the top of the engine (the one that says Nissan Twin Cam Turbo etc etc)
Considering im under the influence of Southern COmfort right now, thats the best response I can come up with.
Enjoy and good luck