1. Doing the big 3 upgrade. Alternator is 140 amps. Wire size is 4 guage, with amp capacity of 150 amps. Should I use a 140 amp to protect the wire and alt?

2. Running a 4 guage wire from the battery to my amp. Amp is protected by a 60 amp fuse. What fuse size should I use put right after the battery? Its to protect the battery, the wire, the car and me, not the amp.