On 14 January 2005, NISMO resurrected the R34 GT-R for one last tour of duty before the introduction of the anticipated next generation GT-R. Labeled as the R34 Z-tune, the NISMO engineers made the car the most powerful road-going GT-R ever created.
Using rebuilt R34s with much technology borrowed from the GT500 Racing GT-Rs and endurance racing GT-Rs, the Z-tune has a 2.8 L twin turbo instead of the stock 2.6 L engine, racing pistons, connecting rods and camshafts, and an upgraded ECU, giving the Z-tune 500 hp (370 kW) and 540 N·m (400 lb·ft) of torque. The car became affectionately known as the "Mother of all GT-Rs" and is carries a price tag of about US$ 170,000. Nismo has stated that this car will be a limited edition, and only 20 will ever be made and sold.
Source: Nissan Press Release