I'm years late to all this but ive been following this car since 2008
the bodykit is mission aero, wheels on the 2008 spec were some wedsports up front (not sure what model) and gpsports gravity gullflames on the rear, as for the engine it was tuned by escort, somewhere in 2010 it got upgraded with s14 turbos and a sequential trans, sadly nowadays its not owned by koyama anymore, it sold last year in an auction, but he still owns some z's, he had many, as seen here: Koyama pictures here