Sources
We've got a plethora (ooh, look at me using big words) of websites devoted to the Sentra, and its performance.
The top being NPM (Nissan Performance Mag - click the image in the top left hand corner of your screen) Mike Young owns Project 200SX GA16DE-T! That car is a monster, he is one of a handful of people turbocharging their GA-series engines.
Also, check out Kojima's Garage over at Sentra.net - You'll find useful tips, and helpful hints there on various how-to deals, including how to read your ECU, Synthetic vs. Dino Oils, and all that other good stuff.
On another note, this is directed to our good buddy MinorThreat. I have to say, you made the biggest mistake - in my opinion - by dropping your Sentra Classic for a Civic. I guess you're one of those kids who has to have what all the other kids have, so they can be cool and fit in with the cool crowd. I'm not knocking Honda one bit, I give them props for making great cars, and in a way I do actually envy their aftermarket support. Sure you can go to a shop, grab an intake kit, or an indiglo emblem, and get it for cheap, but with Nissans, the aftermarket support is growing, and if a part is hard to find, when you do find it though, its a reward. I call it a little bit of hard work, and hunting. The thing about a Sentra, or any Nissan for that matter is when you modify it, and put a little bit of wrenching under the hood, you have that pride that the job was done, and you can reap the rewards. When you hook it up right, the car will turn people's heads and when they ask you what car you have, they're surprised in a good way, and you earn respect. With a Honda, you can go out and get the parts, but almost everyone has it. Its like an army of drones. With a Nissan, you stand out from the crowd. Once again, this is all my personal, and completley biased opinion.