Give those subs approx 1month to loosen up (took my pair tens) and you will notice some air movement.My HDS310s tens in 4.0@32 htz @2 ohms on the Matts HC 300D at approx 1400 rms is pretty nasty in my CRV for a pair of tens.Deff looks like you culd use a bit more power for 4 12s though..But Hey!! You got some lows in and working for you ATM,and be an easy amp swap hopefully?.All hard work is done..Box looks great man.You will tell when those subs loosen up though..Will not be all at same time..Nice work man!