Clipsed wrote:6 1/2" speakers all the way around, and 6x9's do not give out as much umph as 6 1/2's do, so why bother?
Actually, a good 6x9 can out "umph" a 6.5" round one. It's got more cone area. There are some excellent English-designed and Danish-designed 6x9, but they're not intended for automotive use. Generally speaking, you can find higher quality automotive speakers in the 6.5" size because the size is far more popular among the auto manufacturers. But there are some crappy 6.5" speakers out there that are surpassed by the best 6x9.
That said, the parcel tray is a lousy place for speakers. The front and back pressure waves are not adequately isolated from each other and it'll sound like crap. Unless the speakers have their own enclosures.
If you're determined to do this, disconnect the rear door speakers and splice in to the wiring harness (some where before the speaker wires run through the door jam.) That should get music through you 6x9s.