.75"-1" tweeters can be made to fit with custom brackets, but that's not ideal IMO (the last thing I need inches from my ears are straight up tweeters). The OEM speakers are "full range" and they do a decent job of trying to be full range for what they are.

I have an altec lansing ipod dock system that I bought on woot for 20 bucks or something that has 4 1" full range drivers that I want to try if I can actually find the time...

 

I know a local here who installed 2 sets of Memphis tweeters in place of his MY06 roll bar speakers. They match the tweeters from his component set.

 

I think they do too... after owning a 2002 and going to 2006, there is a large difference in sound quality. When riding with the top down, you can hear more of your music.