I ran into the same issues when I did mine. Dash speakers drop right in and sound great. I went with 6x9 Kickers up front and yes I had to remove some plastic. Kickers magnet is deeper than most. And yes they do sit against the speaker grills in the doors. No effect on sound quality. I did have to space them a bit. Rears I went with 5.25's with adapter plates. I'm running a 10" sub so wasn't looking for any bass from rear speakers.
Crutchfield sells wire harnesses that are plug and play for aftermarket speakers for our trucks. I think I got all six harnesses for $30 or so. Eliminates soldering anything. Also it extends the length of the wires which in the dash makes it alot easier to get in. A fellow forum member was kind enough to point this out before I did my install. Glad he did.
Dash:
Speaker Wiring Harnesses For select 1990-up vehicles at Crutchfield.com
Doors: Front and Rear
Speaker Wiring Harnesses For select 1999-up vehicles at Crutchfield.com
Hope this helps guys.
