The reason why I want to go with the alpines is because they go down to 73 hertz, just barely making the cutoff for bass. The cheap pioneer speakers aren't even capable of going that low, no matter what the enclosure. I have a windshield, so hopefully some bass will reverberate from that.
As for waterproofing, I'll buy a 5x7 grille and make sure water can't get in. I'll find a way...
I looked at the Uniqcycle speaker systems and they're no better than what I will have, except about $150 more expensive...Yea, it may sound good, but I don't think it's worth it.