I wanted to upgrade the sub while retaining the stock stereo and speakers. I bought the JL Audio TW1-10 stealth box with a AudioControl 1.300 ACM amplifier, but this pre-tuned Kicker LOC was the key (pun intended) to the build.
This device is awesome. It plugs directly to the stock amp and allows you to add an aftermarket sub and amp combo. When I told my installer about this product, he was a bit skeptical. He was used to taking an off the shelf LOC or DSP and having to splice wires and do hours of tuning himself to make it compatible with the stock head unit. However these guys do all that "pain-in-the-ass" work for you. It is simple just plug and play.
I am using stock speakers and they sound great with the added sub. Full disclosure, my installer did have some issues initially connecting the LOC to the stock amp, as the fittings provided by SGS don't appear to fit. It was a bit of a stressful moment as I thought the project was stalled indefinitely. But a simple 3-way call with SGS and my installer cleared it up. A gentleman named Don from SGS talked to my installer, and said he had to cut off the connector they provided (I hope I am explaining this correctly, as I know nothing about audio electronics) and it would plug right in. After that, the install was seamless, and my stereo system sounds amazing. Highly recommend those who are looking to enhance their system on a moderate budget.