all parts that fit the qr25 sentra will fit our altima without a problem, however you wont get a 7k rpm like the sentra has...their ecu is different. you can install any header that will fit a spec-v as long as it doesnt have the downpipe, i think the stillen one is the only one...and you could put the prevoius gen sentra spec v cams in the altima...i think there is a JWT and a nismo one only...
here's a link
http://www.nissanclub.com/foru....html
here's alink how to do a ghetto sim for the headers...this has worked for many people, once i have money to buy headers from stillen i will do thishttp://forums.evolutionm.net/s...14931