The Non-DSP Stage 1 receives a 2.5 ohm mid-bass while a DSP car receives a 4 ohm mid-bass. This will unfortionately make the mid-bass very weak in your car if using a dsp Stage 1 in your non-DSP equipped car. If you want you can purchase the mid-bass drivers seperately for $160 per pair.
As for the x108 sub system, they are both exactly the same you just get a different set of directions to install on whichever audio system you have. Here's a direct link to the
non-DSP x108 sub-system installation guide.
I hope this helps and feel free to contact me if you have any other questions.