Removing battery wires

OK. I've recently done the 130 amp alternator upgrade and have 2 batteries I'll be running. Both batteries are side post, well, the Optima is side and top post. But, I want to get rid of the stock battery wires and just use the 0 gauge wire I have. How much of a pain in the butt is it to do?

Thanks in advance.

Unless your engine is covered in oil and dirt, it should be fairly easy.
Positive cable is connected to the starter... and the negative is bolted to the block and the frame.

Thanks a ton. I just upgraded all my wiring to 0 gauge and the old stock stuff just doesn't look too pretty anymore. Haha.