I replaced my front speakers using Infinity 62.9i's today (about $60-70 online). Here's what I did (thanks Phil)-
First, pry the switch console off from the side-rear using a putty knife wrapped with masking tape to protect the car, then lift up the back and unhook the front:
Disconnect the connectors - each has a release tab - press it down with a fingernail (or tip of screwdriver) while prying very gently with a flat-blade screwdriver:
Remove the door release handle trim by prying from middle top with a dental pick, and unhook the front:
Remove the bolts behind the switch console area and the door handle area with a 10mm socket. Yank off the interior door panel, starting from the bottom and carefully unhooking the top. Remove three philips screws from the door lever assembly to disconnect it from the panel. Replace any plastic fasteners that stayed on the door sheetmetal instead of coming off with the interior panel. Unplug the speaker connector and remove the factory speaker. Keep the three bolts.
EDIT: Ignore the following portion of this post - I later found that the speakers need to be spaced one inch above the door sheetmetal, like the OEM assemblies, for best sound. See my post later in this thread.
Modify the plastic mounting adapter rings that come with the Infinity 62.9i speakers by using a hacksaw to open up the holes on the shorter two tabs (cut toward the screw holes to form open slots). It helps to make the slots a little larger than the original holes, and to use a reamer or round file to slightly widen the slot in the otherwise untouched longer tab:
Put some thin closed-cell weatherstrip on the back of the mounting ring:
Cut off the existing speaker connector a couple of inches back, and splice on some extension wire.
Left Front: Blue +, Purple -
Right Front: Brown +, Red -
Place the extension wire down the body panel seam into the speaker opening, and screw the adapter ring in place (long tab up) using the factory screws and some additional flat washers:
Connect your speaker wires to the speaker, and tie-wrap the input/crossover block (two opposing slots on bottom side) to the sheetmetal inside the door:
Install the speaker using the four small self-threading (pointy) screws included with the speaker. Be sure to rotate the tweeter so that it points up toward the seats:
I left the tweeter button up (no cut).
I also partially peeled up door's the plastic liner, cutting the adhesive with a razor blade as I went along, and installed some dynamat over the largest openings, then replaced the plastic:
I probably would have benefitted by dynamatting the inside of the outside door skin as well (no dampening there from the factory), and removing the plastic entirely and finishing the door interior sheetmetal with dynamat, but I didn't. My impressions of dynamat after a first use: it's probably about the same as putting down two layers of Nashua butyl flashing tape, then covering with a layer of aluminum foil duct tape. I paid $7/sq ft for a small amount of Dynamat. Two layers of Nashua tape plus one of aluminum tape would be about $2 per square foot. A "door kit" from Amazon is about $4 per square foot. I've ordered one door kit for the back doors and to have a little more to paste on the inside of the front exterior skins.
Lemketron came over as I was finishing up, and we listened to some music in my Leaf, then his, to get a A-B comparison. Both of us thought that the Infinity speakers sounded somewhat better. I'd say they had better definition, a less "flat" sound than the stock speakers.
Was it worth it? For me, yes, but it depends how much time or money you have to spend on somewhat better sound. While the stock speakers were incredibly value-engineered, once I got the door panel off I was impressed with the amount of thought that Nissan put into what was there.
I'll do the rear speakers sometime when my wife is out of town and I have a couple of hours to kill. The fronts took me about four hours! Some of it was figuring out how to use what I had on hand. Guess I'd better keep my day job.
EDIT: They sounded great on my way to work this morning, maybe a little hot on the tweeter. I'll try pushing the treble cut switch with a paper clip through the door grille.