Uhm where did you read that? You can find a 170A fuse. Your best bet is to MATCH. 125A will give you LESS power than your amp needs, starving it, going OVER 170A shouldnt hurt, but still allows more power than your amp will need.
TECHNICALLY you can go with a 125 because you're not going to be using all that power right now anyway, but if you upgraded subs, you'd want a matching/bigger fuse.
You dont want to figure out what fuse to use by adding your amps fuses. You want to go by the rating of the size of wire you use. If you use too large of a fuse, your power line can burn up (taking your car with it) before it blows the fuse. Since you're using a 4awg wire, I'd stay between a 125A and 150A fuse. Seeing that amp is only gonna pull around 65A, you'd be fine with an 80A fuse. But most kits will come with a fuse and fuse holder. I would look for a kit the uses ANL type fuses. The AGU fuses (look like glass tubes) typically have crappy holders that get corroded and add resistance to your line. As for a kit, thats up to you. I spend the good money for good wires because its the backbone of your system.okay phew haha. with that brutus it says to use 4awg wire and it has two 70A fuses on the side. so i would need 140A fuse closest most kits sell are 150A but most kits dont sell 150A fuse with 4awg wire. so do you have a suggested kit? or would it be okay to get 2awg? i dont want to go over like $25 for a wire kit unless its a must. i just think its ridiculous to pay so much for an amp then spend so much on wires for it