I'm not trying to hate on the shop that did your install, but it looks a bit sloppy honestly. x2 on what kranny said, that painted sheet-metal ground should really be moved to something solid, and that fuse/wire routing looks pretty awkward. Those subs are rated somewhere around 500rms, and given the amp, they're probably seeing less than 1kw.
Not trying to rip your system apart, as long as you enjoy it that's all that matters.