well i believe the g20 comes with an sr20de so you can do a turbo but im not sure if that works right or not because i remember rob had a turbo and it never worked right for some reason. what year? im looking at a mid 90s to late 90s g20 myself...but mine wont be raced on.
http://www.nissan-primera.com/
http://www.volny.cz/primera/ <---needs to be translated
http://www.g20.net/forum/
http://www.se-r.net/about/g20/
kay thats allll i know about g20s/primeras
um you can try and see if there are parts and stuff on
www.jimwolftechnology.com and www.nis-knacks.com