2nd gen wiring gurus!

[dubber91]

I am fitting a 13b into a beetle, and the long and short of it is that i have one loom that i KNOW works, and one fitted to the engine going in. Being lazy i figured i\'d whip the loom off the new engine, and just connect up my exsisting loom. The only part of the loom i couldnt remove went under the inlet manifold and over (i presume) to the second injector rail and the water temp sender. I cut off this bit of the loom as i was in a rush, and figured i\'d do the same to my exsisiting loom, after all it was only 8 wires!
Most match up....its just there are 2 black wires of higher gauge than the rest of the wires. Does it matter which these are connected too? Are these just negative wires from each injector, and thus shoulodnt cause a problem?
ITs a cluster of wires with (green black red spots) (green red spots)(dark green white) (black red spots) (orange/brown red spots) (orange black red spots (i think)) and then the two black wires.
I know its vague but how else do i explain??? lol

Chees in advance

Steve