Street:

I know you would recommend a new amp, but is it absolutely required? Are there any efficient aftermarket speakers (Infinity? Alpine?) that could run with 1 ohm impedence and improve the sound of the stock speakers?

The sound difference might not be overwhelming with only speaker upgrades, but I would think it changing out paper speakers would at least be noticeable (unless there is a crossover problem I am not aware of).

This question has been asked in many threads, but never definitively answered. Please provide the final word.

 

If you replace just the speakers without adding an amp to them, you will get less volume than what you have now and a good chance of the speakers sounding rather distorted/scratchy.