I've always been a JBL fan. I went with the 660c cause I got a great price on them. They're a little more toward the higher end then the 6030cs and seem to have a better mid punch. But like I said before I had to trim the speaker opening in the door with metal shears to make them fit because of a bigger speaker cage and magnet. The Infinity 6030cs work just fine without any mods and are a big improvement over the OEM Infinitys. As far as the crossovers go, we just installed them and tested the different settings before buttoning all up. I believe that you can mount the crossovers where you can access them by popping the door panel plate where you would do the “Most Bang” capacitor mod right by the tweeter, which you shouldn’t need with the adjustable crossovers. I haven’t needed to do any adjustments on either setup. The shop that did the Infinity install took around 2 hrs to complete. I ended up dropping the car off on a Saturday afternoon, walked next door to a conveniently located watering hole to watch a college football game and grab some lunch (), and went back to pick her up. Door panels are easy to remove and install. You can find instructions here on the forum. Both setups accepted the OEM speaker covers so no modding of the door panels were needed. And both the sets I quoted are definitely 2 ohms according to their websites.

The OEM amp is a single unit located under the passenger foot carpet. If it does turn out that the amp is bad you can wire the speakers directly into the Clarion pre-amps. Some members will say they prefer wiring direct which gives better control over left/right and fade adjustments. The OEM amp doesn’t allow fading between the woofers and the door speakers if I’m not mistaken.

One other thing I might add is with the door panels off, it's a good idea to install some sound deadening material. My doors do rattle a little at higher sound levels and I may go back in and apply some.