Custom box builder for 96 impala ss it use to have a custom box before so it has a square box hole cut out already for the custom box ....I don't know if I'm in the right spot or where do I go ,I'm new to this sight so please any help would be great also I have 2 12inch subs alpine type r 2ohs and a alpine 1200watt rms at 2ohs I was wondering if this is a good amp for my subs