Nissan’s motorsport and tuning division Nismo originally designed the Z-tune in 2002 as Nissan was putting an end to the R34 Skyline production. First built in 2003 and based on a 2002 Skyline GT-R V-Spec II, it featured a concept RB26DETT ‘Z1′ engine, with the cylinder diameter bored out, and a redesigned, longer-stroke crankshaft. The engine was now a 2.8-liter producing about 500 hp (370 kW).
For Nismo’s 20th anniversary, the company repurchased 20 used R34 GT-R V-Specs and revised the engines to create the 'Z2’ version of the Z-Tune engine. It also sported the same functional components used in Nismo’s GT500 racing cars, such as engine bay vents on the hood and fenders, as well as wider fenders for wider wheels. The suspension setup was firmed up, and special Brembo brakes were fitted to the car.
The fanatical Nismo engineers did not leave it at that. The cars were also completely stripped-out and re-built from the chassis up. The chassis received additional reinforcement and seam welding in specific parts. Carbon-fiber was added strategically to reduce weight, and the suspension, engine and drivetrain were all thoroughly reworked. All this work essentially turned the Z-Tune into a customized handmade road racer; it is consequently the most expensive GT-R ever made.

Specifications:

Engine: 2771 cc DOHC 24-valve inline-6
Horsepower: 500 hp (368kW) at 6800rpm
Torque: 399 lbft (540 Nm) at 5200rpm
Injection: Electronic Fuel Injection, Twin turbochargers
Drivetrain: Front-engine, Four-wheel drive
Transmission :6-speed manual
Curb weight: 1600 kg
Dimensions: length 4600 width 1894 height 1359 mm, Wheelbase 2664mm
Suspension: Multilink front, Multilink rear
Tyres: 265/35 ZR18
Model code: BNR34 Z-tune