question on wiring two amps

i recently bought boss pd-3000 and mtx thunder 564 amps and a boss cap20c power capacitor. my question is...what is the best way to hook up the two amps. both amps of 4 gauge power and ground terminals, yet all the the distribution blocks only have 4 gauge input and 8 gauge out put. does this mean because of the split with in the block and the short distance from the two amps to the block mean i can use a 4 gauge power wire from the battery to the distribution block wit the power cap  hooked up to the 4 gauge wire between the battery and distribuition block and then 8 gauge wire from the distribution block to the amps. if i use 8 gauge wires from the distribution block to the amps then do i use 4 or 8 gauge wire for the ground wires of the amps. thanks for thelp.

you can find a power distribution block with 4 gauge outputs.  you can find them with even bigger outputs than that, i think up to 1/0 gauge.  you just didnt find a store that sells them.  i know lightning audio makes them bc i have one.  if you cant find one at a local shop, you can order off the internet.  the one i have has two 2gauge inputs and three 4gauge outputs.      http://www.thezeb.com/caraudio/lightningaudioblocks.html   try that web link and look at model GD3.  it has two 1/0 gauge inputs and 3 4gauge outputs.