So I've gone for a speaker upgrade, got hold of some 5.25 inch hertz that fit nice and snug without any difficult modifications. The rears are a coaxial system with about 40rms power. Also dynamat soundproofed the surroundings here are a few pics...
Old and new

Depth

Panels off

Soundproofing in

Snug fit
All sounds much better now and can crank up the volume!!