I’m not an audio guru, but I’ll throw out my opinion anyway.
The advice you got on wire size seems just fine. Often people blame wire size on faulty connections, solder and ring terminals are your friend.
I don’t have much doubt you are in HO alternator territory, adding a cap or doing the big three won’t change much. However if I were you I’d beef up the grounding on your GP. The stock fender well ground on all GPs are for $h!t. Remove the ground wire at the fender well and grind/sand the connection down to bare metal. That area gets quite a bit of grime build up, and it comes painted from the factory leaving about 1 square millimeter of metal for the actual connection.Go buy yourself a 6 gauge cable about 42 inches long, and run it from the base of your alternator to that fender well ground you just fixed. And bang, now you have a much improved system grounding for like $5.
Pop in a new battery see how it goes, just watch your voltage. If you don’t have enough juice, save yourself the disappointment of buying a useless cap and put the money in a HO alternator.
As far as the system, seems super duper. I’d love to have the sub in my ride.
