Hey, I'm might be buying a Nissan Altima 3.5 SE 2004. And was going to throw on a speed chip, new air intake and new a exhaust to better the performance. Stock it is already 290 HP (6600 rpms) If i get decent chip, intake, and exhaust, what HP do you think i'll be sitting at?  

kasper,

first off that car does not make 290hp. it's about 245. i currently own one. Your better off buying the SE-R. if you get a newer SE-R you will be able to play with stock 350z on the straights.

another con...
that generation of the altima is pretty bad. i have heard a lot of owners complaining about oil consumption and engine failure. it was caused by a hanger pin that would catch debris and burn a hole in your exhaust system somewhere and send debris flying back into the engine. if i were you i would avoid this generation of altimas and go for the 2k5 or newer.  

yeah go look at the recall list on any modern nissan from like 05 and up