Yes, I know this topic has been discussed numerous times and it has been confirmed that the 05-06 bumper will fit on an 03-04. So the vice versa will be true, however, I am concerned that the nismo rear lip might have trouble fitting over the lower part of 05-06 quarter panel. I believe the lines are the same on the quarter panel all thoughout even though its black plastic on the 03-04, but I haven't compared them side by side.

Has anybody attempted this? Well, I've already got the bumper on the way, and I'm about to make the order for the lip, so if no one has tried, I guess I'll be the guinea pig. BTW, I have my Sarona roof spoiler for sale in the marketplace so check that out.

 

I can't tell you now about the fitment, but I should be able to find out tomorrow. One of the guys at my work has a 2005 and I can compare it to my 2004. I think you're correct in saying that the bumpers are similar, save for the black plastic.

It looks like people named Alex are the guinea pigs on here. I'm attempting to get a NISMO front bumper from a coupe, cut out the vents and bottom, plastic weld it to the sedan bumper (minus the bottom) and see how it works out. All of the bumpers for the 03-04 look too aftermarket-ish.

 

The 05/06 lower bumper is not rounded like the 03/04 when I tried to mount the stillen rear valence I was about 5 inches too short on the passenger side I believe the same would hold true for the Nismo. I do recall on person being able to successfully get the Nismo to fit his 05 but that too some modifications which if you can find a body shop dedicated enough to attempt is doable. Swapping the bumper might just be the best and cheapest option.