I definitely want it louder and clearer with both top on and off.
JMO, but I do not think it is much louder with just upgrading the speakers.
I'm not looking for a perfect audiophile setup just something that's relatively good.
The problem is the word "relative". I upgraded the speakers to the kickers. I then added the amp I mentioned above. I then added a 10" sub. Now, I'm in the middle of changing the whole thing to a 4200NEX, 4x100W amp, Polk 4.5" speakers and 2x10" subs. I purchased a jeep for my wife so I'm moving all my existing equipment to her jeep, and she'll be perfectly happy with it, but I wasn't.
I have considered an amp for the interior four speakers.
I understand that the output of aftermarket head units can be 2x-3x the factory head unit. With the kickers, this may be enough. I have not tried this, so I can't speak to it. Again, "relative". Might be worth researching if you just want a little more.
I'm honestly not sure if want to do a subwoofer. Which 8" sub are you referring to?
I think it's an alpine that you can buy with the mounting bracket for under the drivers seat. Check Quadratec, as I know they sell it.
I also will be eventually upgrading the factory head unit to a touch screen.
A lot of people recommend you do this first. I didn't and now I think I went about mine completely backwards.
Just be sure that you are sure on what you want and it'll save you a lot of money/time/frustration. Maybe you have a local club and you can check out what some other guys have done. Then again, that might cost you a lot of money.