omg rust on 32's is crazy. ive got a GTR and thank god im doin a full ground-up rebuild. i found two rust holes on each side on the floor where u guys were talking about. I also hav rust under the rear wheel arches in the bottom corners on both sides. ive got some pics from the inside, hopefully yours isnt this bad, but might be whats under your carpet.
Its really hard to find, i wouldnt have found it if i didn grind away all of the floor sealant, so u guys should do that as well. As for the wheel arches there was just a big hole that was easier to see. See the pic of where i had to fill it with seam sealer.