Dude, it's genuine.. this engine is from GT51R, an R33 GTR originally from Perth which produced 647 horsepower at all four wheels with the T51R SPL turbo.. Check out the specs on X-Speed http://www.xspeed.com.au/ssport/41gtr/
Nathan traded in GT51R with Ultimate Performance Imports here in Melbourne for an R32 GTR wide body which he's also sold now.... and got himself a BMW M3
The engine/performance mods done on GT51R in Perth were not done very well by the people who worked on the car over there, and it needed alot of work to fix up their mistakes.
Swweeet car though