do you even know what your talking about.... Full gain does not = normal rms rating. Full gain = blown subs/amps. Gains should be set matching the input voltage of your head unit.
Op, you bought a very basic bottom of the line beginner setup. Not sure how loud you want it but It'll do for some bass fill. That SSL amp is for speakers and tweeters and its in the junk category of amps so you'll be lucky seeing 50 rms a channel out of it. The subs are not that great either.
What bmk6795 meant about the box is that its a pre built cookie cutter box. These are generally poor designed boxes that does not have enough port area and is tuned pretty high so it wont dig into lower notes and generally sound not as pleasing.
If you have high expectations of loud bass, you might as well sell it all and start over with proper equipment. If you dont care and just want some bass fill then you can keep that setup and run it.
that setup is not worth anymore then 120 to be honest.