n1 was the sneaky race homologated model that nissan built on top of r32 vspec 1 and vspec 2.
it was basically the same except for larger turbos (really crap by modern standards, but a fair bit bigger than the base model had). few other changes like the body kit (nostrils in the bonnet, side skirts and rear lip under the spoiler), no rear wiper, no air con, no abs.
33 and 34 also had n1 and they got progressively sneakier