[Jack21]

Basically, you want speakers with the highest RMS wattage handling capacity, and an amp that will power them in the trunk. Good ones, like Infinity Kappas, Polk, and similar put out the volume and oomph without distortion. Your run-of-the-mill Pioneer, Jensen, Kenwood, Sony won't get it.

CR's have a small back shelf that small enclosures fit on quite well. Others might need cutouts.

Just remember, this is a Cobra, not a Caddilac. Sitting in rush hour traffic up to about 35 - 50 MPH, you'll hear it if you turn it up. After that, all you'll hear is engine, wind, and sidepipes.