On a similar note, I discovered that my rear tweeters in my '95 SSE were bad. I decided that 3.5" replacements would sound nice, so I bought a pair of 3.5" Infinity Reference 2-ways.
I needed to remove large amounts of the mounting bracket (underneath the grill) to get the speakers to fit. Everything went back together well. The mounting depth is just a tad shallow for the speakers, so the grills stick up a little bit. However, it isn't noticeable unless I point it out. Everything sounds MUCH better, so I can tolerate an almost imperceptible deformity.