200w into 4 ohms is very useful and will do well for you.
Most of the noise is made within the first 100 watts.
To sound "twice as loud" (+10db) you need 2,000 watts and/or sufficient speakers to handle this amount of power.
A pair of 8-ohm cabs will give you a total impedance of 4-ohms.
Two cabs will give you a lot of noise and the flexibility to take only a single cab as needed.
You get a +6dB boost when you plug in a 2nd identical cab.
3dB from 2x more power handling, and another 3dB from the doubling of cone area.
When I die, I hope my wife does not sell all my toys for what I said I paid for them...