A $500 intake will close the power margin between the 6 and Altima, for a combined price lower than the Altima... and the Altima still handles like a boat.
OK... so I am a staunch fan of the 6. To me, the Altima is a 2nd class car in comparison.
The additional body styles of the 6 over the Altima give a lot more versatility... the 5-door has huge cargo space, while having the sportiest look of all.
Turning circle... I don't notice it. Definitely a drive and see how you feel about it on your own.
The side crash test was performed w/o side airbags, and was still decent. 2005 models come with side airbags standard.