Custom Box help

If this is a sealed box you are going to need more power to match what you originally had with the 4-port bandpass box.

I ordered a kenwood 600 amp hope that will do some good

Do you know the cu/ft. specs for the subs in a sealed box?  What did you use to seal your seams with?  Is it a good seal?  If you are just screwing on the plexiglass front cover you are not getting a good seal.  Apply clear caulking or adhesive sealer to the front before mounting the plexiglass to it, or reach in and seal from the inside once you take the subs out.  1/4" plexiglass is pretty thin for this type of application, I sugget you go to a thicker plexiglass.  A sealed box is under a lot of pressure if sealed properly.  Adding stuffing into the box would make the subs sound as if they were actually in a larger box, although I'm sure you added the Plexi to see the subs not the stuffing right?   The box is a very important component....you could have the best subs in the world but if your box leaks excessively or is not built properly the subs will suck!

If you still need more after installing the kenwood amp you could wire the subs parallel into 2-Ohm (assuming they are 4-Ohms each) to pull more power from the amp, although more heat and THD will be produced.  Oh yea, make sure the amp can handle a 2-Ohm setup before attempting. 

cu/ft. I believe I made right when building the box, I just sealed the box yesterday with caulking, it actually sounds alittle better..I guess air was escaping when I "temp" hooked it up to test it.  I have yet to seal the plexi glass on with caulking  because I may add lights in the box, the 22 screws for it should hold the plexi good for now.  Stuffing would be nice but yes I added the plexi to see the subs.

thanks for all advice