I have a Pioneer F900bt, 2x Hertz comp speakers, 2 x Hertz Coax speakers, 4way JL Audio 4way Amp, new wiring all round. I have kept the Bose Sub + Amp for now as it has cost me close to £1,500 including fitting already
Sounds unbelievable good compared to the standard Bose or even a new HU with the Bose...
I am sure there was someone from Hull who was selling a sub enclosure that he had made... was a while back but I dont think he sold it, might be a good starting point
if you are on a budget then just get a single din and just the front speakers, a Zed is so small you could live without the rears until you can get some...