I replaced my front tweeters and all 4 door speakers back in January with Infinity 6532ix 6.5" 2-way speakers and Infinity Reference 375TX tweeters. They were all 50% off for Black Friday, so I got them all for $150. The back doors also have separate tweeters, but I didn't get replacements for those.
While the door speakers were pretty easy to swap out, the tweeters required more work than I thought they would.
The A-pillars were pretty easy to remove (once I found proper documentation). The Inifinity tweeters were just a tad larger in diameter, so I had to file and sand the mounting holes just a tad to get them to fit. Plus you have to cut the existing connectors off the wires that connect to the tweeters since they're a small molex-type connector that apparently only connect to Honda stock tweeters. You also need to use the supplied crossovers, otherwise it tries to push the full frequency range into them. I thought that might have been taken care of in the head unit, but apparently not.
Once installed, I found them to be a little too loud compared to the door speakers, so I ended up making a 6dB pad with a pair of 10w resistors, and now everything sounds balanced to me. Getting the crossovers and resistors anchored onto the A-pillar is also a little tricky, you need the strong 3M double-sided foam tape.
I'm attaching a few photos I took when I first installed the tweeters and crossovers, but before I added the 6dB pads. If I get a chance, maybe I can yank the pillars off and get a shot with everything in there.
It may not sound as good as a system with a new amp installed, but it's a lot better than the sound from the stock speakers.