my z31 (original v6) converted to a straight 6 engine. trust me v6 to straight 6 engine conversion is not an easy task. not cheap also (i'm not suggesting that u might not have enough budget. its just too big a hassle). better just buy a car that originally comes with straight 6, like what nicole suggested, a skyline R34 gtt. or just use a z33 without converting the engine. stock engine is so nice already. road tax is only once a year hehehe