I'd get a better headunit, and use components rather than 4x6's, unless you can only use 4x6" speakers, and don't want to have components custum installed...
the only reason i have the jvc hu is because it was dirt cheap ($180)brand new, and it has an SD card slot, right now all i have is the 4x6's and i dont really want to have components custom installed but i do have room for 2 6.5's so i will get some soon.
for the price it's a good ehad unit. I used to sell JVC at my shop. Never really had a problem with them, and they've gotten better looking since back then. Just didn't have the features some of the other brands did, and back then, they were really ugly always cheap though.. fit a lot of budget systems