The cabs aren't happy or the drivers aren't happy? If its just the drivers, have a look at the specs. You might find that a more efficient driver will solve the problem. 3db is double. A more efficient driver will run cooler too, which means that the coil resistance stays low and you get more out put.
As for building cabs:- if you are buying drivers AND building a cabinet, why not just buy a good speaker that is designed to run with good drivers? You will get better frequency response that you would get by chance.
What amp are you using?
TRB5 MK1, TRB1005F