crypt2k wrote:i thought that Nismo stood for NISsan MOtorsports...
It does and it doesn't. Nismo is short for Nissan Motorsports International. It is the company, based in Japan that tunes all OEM Nissan cars. They develop racing motors, as well as a large development on street tuning.
Nissan Motorsports North America (the Nissan Motorsports that US dealer's can get stuff from) does no development. They simply sell, for the most part, OEM stock Nissan parts. The only difference between them and Nissan Genuine, is that Nissan Motorsports can get a lot of parts from cars that were never sold in the U.S. For instance, they can order you an OEM SR20DET exhaust manifold. They sell very few street tuning parts, unlike Nismo.
Basically, if you're looking to build a racecar, Nissan Motorsports is the place to look (fiberglass body panels, high compression pistons, etc). But if you're looking to make your street car faster, Nismo is where you wanna look. Also, if you're looking to build a custom motor with state of the art technology for a very competitive racing series (not SCCA), then Nismo may also be a place to look.