N1 = Blueprinted Race Specification Engine.
N1 Block (N1 Block is identified by the number 24U stamped on it as opposed to 05U)
N1 Twin Turbos (Metal Ball Bearing, from factory 1.1 Bar boost = 15.9 Psi)
N1 Reinforced Cylinder Block
N1 Pistons
N1 Piston Rings
N1 Con-rods
N1 Oil Pump
N1 Water Pump
N1 Exhaust Manifold.
No ABS, A/C, Radio/Cd, rear wiper, carpets and a factory standard Carbon Fibre bonnet was installed to reduce weight.
V-Spec II Nur's and M-Spec Nur's are based on the V-Spec II N1's but WITH ABS, A/C, Radio/Cd, rear wiper, carpets and a factory standard Carbon Fibre bonnet.
Pics ask Iron Chef, he's got one... Damnit I want! LOL!
I believe the N1 Engines are hand built so they are very refined / well balanced engines.