[QUOTE=russsims;313609]Not heard of the brand of your component speakers before. Get Car Audio magazine, attend SEMA and CES and not seen this brand in attendance. Did you do the install yourself or an audio shop do the work?
I installed rear speakers and personally found them a waste of money and have gone with full front staging but with a better sub. Full Dynamat Extreme interior helped greatly--tightening up things--really hear the difference with the top up.
At some point will have a custom sub enclosure made for a 10 or 12". Have found my Alpine 4 channel at 150 watts/channel, bridged for the sub more than enough and only needed the one amp behind the passenger seat so as not to require a separate amp for the sub.
For those interested in installing bigger subs, check out the thread in the Solstice forum in the sound modification section where we posted a write up from a audio shop that installed 10" subs behind the driver and passenger seats. Looks like they cut out the back wall as you did and fabricated a larger enclosure. They also installed the Alpine 4 channel amp in the waterfall area so as not to install in the trunk--do sure I like that piece of the install job but interesting. Two 10" Sub Install - Pontiac Solstice Forum
CDT Audio is not main stream, kinda under the radar. In fact I took mine to a shop and the installer hadn't heard of them either. He said he was sold on them after hearing them though. He said they were better than the OZ Audios they usually go high-end with.
The 4's I have are very loud and clear. Maybe part of the reason they are so loud is I sit with my seats all the way back and the speakers are right there.
One amp instead of two just didn't work for my set-up. I couldn't find a single amp that matched up to my components and sub very well so that's why I split them up. I think you will always be better off doing it that way because you don't tax the amp as much and the quality at least in theory should be better. The draw back of course is less space especially in our car with a second amp but I can still fit my golf clubs in the back so I am golden.
There is a good amount of space when you cut the back out so you don't necessarily have to go with a shallowmount but the question is, will you provide the sub with enough space (air) for good sound?