I used silcon sealant myself. I did a test run previously with epoxy, but found it did not adhear to the plastic too well. It popper apart in my hands.

What I finally wound up with is the 4" speaker form the Infinity 4269CFP (4x6 plate) and the Infinity 109T tweater. It did take a lot of modification with a dremel to fit the 1" tweeter. But the sound is amazing.
I used a Helix B five to replace the stock amplifier. The headunit is a Kenwood DNX9980HD. Beofe I repalced the stock amplifier I ran the same speakers for a weekend trip. There is a BIG difference int he sound quality to be gained by repalcing the stock amplifier. I can't say about the stock radio since my had already been repalced by a low end Sony unit for the PO SIrrius radio.
I'm going to take anothjer look at the doors this weekend and see if I can remove the wiring harness and reconfigure it for the 12 Ga speaker wire to power the kicker 6.5" subwoofers I bought. I didn't find the stock (sub?) woofers to do much for the sound system to begin with so replacing them with better speakers didn't seem like a worthwhile effort.