Hey Wedoo2, Thanks for the compliment. Much appreciated!
If I recall, the stock system was plenty loud. Perhaps even a little louder than what I now have. But there was much more distortion from either the stock speakers or the amp. Probably both. The Polk speakers were the first thing I swapped to and they are up to the task. I'm not sure adding another amp to the stock system would do much good. The stock radio seemed to have more than enough juice to push the stock speakers. I would suspect that adding an amp alone would not be fruitful.
But you can try hooking up an old car head unit to the stock speakers and see if that is an improvement. The head unit I first used was a 200 watt RMS pioneer but that wasn't enough watts..... plenty of distortion at high volume. Mind you, at 50 mph, the pioneer head unit was at max volume.
But if you want to add an amp to the stock system, you would need to cut the existing speaker wires and join them to the output wires from the amp. Not very hard to do.
So it goes like this....
You will have 4 pairs or wires coming from the stock radio to the 4 speakers.
Cut those where convenient. ( don't worry, you can always rejoin them if you cut it in a sub-optimal position).
So now you have 4 pairs of wires coming out from the stock radio... you connect those to the input of the new amplifier.
You also have 4 pairs of wires coming from the speakers (cos you just cut the original speaker wires in half). You join those 4 pairs of wires to the output of the new amplifier.
As for wattage and blowing up speakers, I suspect that doing it like this could damage the speakers if you go too loud. There could also be issues with Ohms and what-not which I'm not clear about.
I do know that the Boss 900b amp which I use pushes the Polk speakers just fine even to max volume. The Polks seem ok.. But who knows, they may blow tomorrow!