So I just read Andy2434 install. But I did mine diffrently so I thought I would share. I have an 05 sedan and thought it would be easier, but I wanted the best matching end result so I suffered the time involved.
The first thing to do is to remove the wheatherstripping. The sheetmetal is too high where the wheatherstripping was and I wanted it to match the way it was on the other side as much as possiable. So it needs to be trimmed. Marked with a sharpie and cut. Then use some primer on the raw metal.
Next you have to drill two holes for the white plastic L bracket. Just like it is on the other side of the car. This was actually a pain because some lines are almost in the way. Drilling through sheetmetal is a pain, and I almost ventalited my Z tube twice when the drill bit finally broke through. So take your time. Again prime the new holes.
Now you have to trim the back lip of the cover. This was a lot easier then the metal parts. And you need to cut/grind off a ridge in that same position on the cars plastic lip so the cover will set flat (sorry no picture).
Remove the rubber plug on the fender.
Now you can stop working and install with just the two push clips as retainers (and three as cosmetic), or you can go that unnessary mile like me. To follow....

 

More for those with more time.
I made a plastic piece out of black sentra to act as a lip and retainer for the back edge of the cover to rest on (compared to nothing). It turned out ok but I tried 5 types of glues so far with no luck getting a strong bond between it and the bottom of the plastic factory edge. Too waxy a plastic. Any suggestions?
It all turned out nice and I love the way it looks in the end. Why did it not come that way?

 

Wow you got the L bracket? I didn't get one and Chad said he didn't have any. This upsets me.

 

Well, I originally asked him if he could beat Grubbs price. But he said he did not have the bracket. I wanted it complete so I ordered it from Grubbs. A day after I got it he listed his kit (for half what I paid, sucks for me). I still have the bag with part # the bracket came in. When I get home I will get the #. Any Infinity/Nissan dealer should be able to get it. I wanted it to look as factory as possiable.

 

Why do people trim sheet metal? I didnt have to on my coupe.

 

Placing the cover on the metal as is would have raised that spot 1/2". Andy2434 got around that by trimming that whole side off the cover so it did not set on the sheet metal. Either way cutting should be done.
The hood may still close with the added height but I wanted it to match the other side. Maybe a coupe or other years are diffrent?

 

very nice, I was considering cutting the sheetmetal too but chickened out. I didn't want to hack up the car. I went as far as marking everything out and taking out the grinder but lost my nerve. As far as the gluing the two pieces of plastic, did you try epoxy or PVC solvent weld (stuff for PVC pipes, should melt the two plastic pieces together).

For the guys that go the trim plastic route, here's a tip. Use a utility knife to score the plastic where you want to cut it and bend it in the opposite direction. It will snap off with a clean cut, much better then can be achieved by cutting. This works for all types of plastic.

 

Yea I know cutting metal on a new car is something I try and avoid. But thats how it would have looked if it came from the factory installed, and I wanted to retain that symmetry of the two covers. I started a long cut with a Dremel and then bent the metal back and forth until it snapped off, then sanded it down a bit. So far I have tried Duco super glue, Duco 2 part epoxy, Testors plastic epoxy, 3M black rubber adhesive, Testors plastic model glue, etc.. The PCV edhesive was next on my list to try on some scrap pieces.

 

Try JB weld. The stuf actually "melts"plastic. I've used it on acrylic tanks and it holds. I mean HOLDS

 

Nice install. I went the quick and easy way.. I went to town with the dremmel, and mine has 1.5 clips holdng it down ... I have an 06 and did not want to drill..

 

As has been requested by some members. The part # for the white plastic L bracket is 64880-AL500.

 

I'm not sure if I missed something... I have an 03.5 and I didn't trim anything. The new cover fits inside the metal and the weather stripping went over both. Here are the pics. I don't see the difference?!?!

 

I trimmed the metal just like John. I'd like to add that bracket. The rear support looks great too. Try JB Weld Kwik. Lightly sand the two surfaces (just enough to rough them up a bit), clean with alcohol, and apply the JB Weld. Worked well on my lower front bumper grilles.

 

slider, you probably got yours from Grubbs or somewhere else that was already precut. Mots sell them precut already so we don't have to do it.

 

I got mine from grubbs and their were no mods done to the cover before I got it. I cant attest for other years or for the coupe but on mine this was the way to go.