None of the stereo components in my truck are stock. I did not have the Infinity system, but do now. Stock speaker cones are made of paper, and the factory Infinity is no exception.
I have a Kenwood cassett deck (which is about 3 years old and has been in four of my vehicles now) with a Kenwood 10-disc changer. The front speakers are Infinity's, and are a component set-up (sort of like the factory Infinity system, except I mounted the tweeters in the door panel, about 6 inches above the woofer), and the rear door speakers are Infinity two-way. I have an MTX 4 channel amp driving all four door speakers, and an old Sony 150 amp driving an MTX 10" sub. The sub is in a bandpass box made by Q-Logic, and sits between the front and back seats on the transmission hump. It isn't the one that mounts there, but just sets in there for easy removal.
If I had it to do over again, I wouldn't use Infinity again. They don't handle much power very well. I would use Polk or JBL.