One of my rear speakers bit the dust a while ago, so I pulled it out and contemplated how I wanted to fix it. I drove around for a while without it and didn't really miss it that much.
Anyhow, I finally got off my duff and started spending some time fixing other issues on my ti instead of my other project cars and the rear speaker was one that needed to be addressed. What expedited the matter was managing to get some radio reception (another story/thread entirely) with some bass and it was only a few minutes before it was the undoing of the remaining rear speaker...
I knew I was not going to buy another set of stock speakers but it was not too interested the 5 1/4" install that I saw. I know it is standard car audio install practice but I wanted to keep my install as close to stock as possible and invest as little as possible since the ti is just the daily-driver.
I found a pair of used 4.5" Eclipse speakers on eBay and knowing the brand reputation (I am/was quite fond of their minimalistic head unit design - good electronics/amplifiers, simple display and big knobs that are easy to feel) bid on them and scored the pair for $17 shipped off eBay.
Now, to the installation and some pretty pictures which detail how I decided to install them, which I think is unique. I don't recall seeing this method when I last looked, so if someone else has already done this and it's old news, my apologies...
First of all, I realized that while the stock speakers are not a single unit and the speaker can be separated from the bracket/enclosure. They are glued together, so VERY CAREFULLY using a sharp utility knife, you can break the glue and once you are done, release the catches (if they don't break) and rotate the speaker to separate it from the bracket. Again, be VERY CAREFUL with the knife, as you will have to apply significant pressure to break the glue so be patient and work SLOWLY.
Here is the end result, speaker and bracket are separated
The speakers I got came as such, which I separated from the speaker and removed the "grill"
I then took the install "ring" without "grill" and used the one item no ti owner can do without: JB Weld!
When I glued the ring to the existing bracket, I did so such that the screw holes were aligned with the tabs from the old speaker so you could slip the screws in. Once the glue started to set, I put the speaker in the trim ring "inverted" so that it weighted the whole thing down as a clamp as I didn't have much success getting standard clamps to hold the two pieces together without sliding the two pieces.
To conclude, install the speaker to ring after the JB Weld cures (6-ish hours, overnight preferable), solder terminal connectors salvaged from old speaker to new speaker (making sure to get the polarity correct - the black striped wire is "+" and generally the larger spade connector on aftermarket speakers but I verified by briefly pulsing both with a D-cell 1.5V battery and ensuring both moved "out" the same way), install assembly back in car and enjoy tunes with bass again.