I know nada about the Stillen exhaust for the second-gen, but if it's anything like their exhaust for the first-gen, I'd say it's not worth it. I had it for about two years on my '94 GXE and it looked funny, didn't sound all that great, and started to rust in a few spots pretty quick. As Peterson, I believe, said: it's a big tip welded onto a muffler. That's all.
SCC's waste of a Project Altima (95 auto rental car) produced 13.7 wheel hp from the JWT intake and Stillen muffler, though it goes to show that probably ANY straight through muffler could produce the same share of results (whatever % the muffler played) as the Stillen.
i had the stillen on my 1st alty. the center core of the muffler rusted out in less than a year, and it sounded horrible. i called stillen and they wouldnt do shit for me either except sell me another one at cost.