[Christ]

MB quartz mid-bass drivers all around. You'll need to adapt your door buckets to accept 6" component speakers, though. (You have 5.25" all around).

If you want decent bass, you can sub the rear speakers for 6x9's, and no one will notice. It's a pretty easy swap, but I don't have a writeup for it.. you can see how it works just by looking at the speaker mounting bucket, though.

If you don't mind pulling up your carpet and adding some weight, consider laying down felt paper on the floor of the car, under the carpet. It will help with road noise. (Yes, rolled-roofing).

When you mod the door speaker buckets, put a shield on the top of them, so that water can't contact them dripping through the window channel. (Do this even if you don't mod them, some have "vents" on them that allow water in.)

If you only intend to use the iPod, no radio or CD's, you don't need a head unit at all.

What you'll do in this case is get a 4 channel amplifier, run all your speakers through it, and get a headphone cable that splits into RCA inputs. (You can get them just about anywhere.) Run your iPod into your amplifier, and use the equalizer in the iPod to control sound quality. Tune the amp as necessary, but try to keep it from filtering lows.

If you can't get an amp that doesn't filter lows, you can run 2 amps, and use the line-out to chain them (iPod to front speaker amp, line-out from amp1 to amp2 (rear speakers) and set the front to highs, and the rear to lows. Set the volumes according to your tastes.

Benefit - no head unit to get stolen, less wiring, less current draw, easier to hide amps/iPod in small spaces that are normally unused, can use the old DIN slot for a cup holder mod from a Taurus (PM me, I'll send you one for the cost of shipping.)

EDIT - You can replace the MBQuart speakers with Sony Xplod series speakers from Wally World... that will save you some money, and in all honesty, they're not that bad... We have them in my wife's car. They're definitely not audiophile speakers, but they'll get you through a rough ride, and they have a decent sound. (My wife's 6x9's will make enough bass to hear it about 200 feet away, with the windows up.)