I was wondering if having the battery in the trunk next to subs and amps has any negative effect? Like static or magnetic interference or my battery is ganna blow up cause of all the vibrations or some shit like that. (It’s going to be in a real battery box.)
Nope.
If anything, having the battery closer to your amp will just shorten the distance the current will have to travel.
No gain in power output will happen, maybe a gain if you had shit sized power wire before.