[Rod2Rice]

No reason to not swap out the head unit because of warranty. It wont affect anything, and worst case just hold onto the stock unit in case you need to swap it back in. I replaced my head unit before the speakers, and the sound was better, but only marginal. New speaker really brought out the better sound. And in my opinion, the stock tweeters are very muddy sounding, some aftermarkets will really make the highs shine.

the front setup really isnt a true component setup in my mind. There are no crossovers, just a resistor wired into the tweeter to block the lows. The 4 other speakers outside of the tweeters are all the same, no difference. If you wanted to put full range speakers up front it would sound OK, but I would leave the stock tweeter disconnected.