Well I relocated my battery to the trunk of my car. I have a optima yellow top. All I really did was remove the OEM mount, made some brackets and welded it into the trunk. Then used all OEM hardware to bolt it down. It shouldnt go anywhere.
Anyway Im using 4 gauge wire the entire way, for power and ground. (I had 25ft of brand new 4 gauge in my room so i used it).

My question is, I have a 80amp Rockford Fosgate fuse I guess you want to call it that. Its the type that when it blows it just unhooks a tab and pops out. Can I use that inline of the + wire incase a short, or should I get something smaller?

Also I went to a few auto parts stores and tried to go to a speaker store but it was closed. I wanted to T off the 4 gauge wire, because how it is originally there is the + comming off the battery and goes to the starter, then there is also a wire that goes to the fuse box right off of the battery clamp. I couldnt get a T or anything and its going to be super hard to solder 4 gauge wire, so I took the wire directly from the battery and went to the starter post like OEM, then at the same location I put the end of the wire going to the fuse box at that point, then up to the fuse box.
If you can follow what im saying, this wont cause a issue with the fuse box will it? My car starts and runs perfect no slow cranking, no dim lights.