You forgot the crosovers? Which are a mayor pain when trying to upgrade. They are included in the standard and HK amps rigth?. And I think the head unit has balanced outputs, not line level? Assuming you can get an adapter (balanced to unbalanced), and 2 crossovers, That would add about 120(2x60) + 50 + install, say 250 Agree, bang for the buck, is worth it.