There's an aftermarket skin on this dash. The vinyl underneath was cracked, but the foam sort of intact. The factory dash is bad enough - trying to push high frequencies through small foam-lined holes can't work. Then the aftermarket overlay has even smaller holes and the pattern doesn't line up exactly with the factory ones. So you have to knock out a lot of the factory grid work. So with speakers under the dash, you have to have tweeters somewhere else.
You'll see what I'm doing with some modest Pioneer 5 1/4" coaxials (TS-G1345R), but the best way to do it would be with component speakers, each with their own grill. See, coaxial speakers suck because of the exposed pole piece that lets dirt and iron particles get stuck in the voice coil gap. They SHOULD mount the tweeter on a bridge across the top and use a real dust cap. In my revamp of the K5 system, I pulled out 2 bad speakers from voice coil contamination. So a big part of the challenge now (and delay) is to dust-proof the upward facing speakers while still having a presentable install.