thanks..i did nearly the same setup in another avalanche just not out of fiberglass and it sounded just fine..if i go sit in the cargo area of my car with the sub...all i hear is bass..A 12’ sub firing up/out/forward and only 36” from your head You are only going to hear the mechanics’ of the sub working not the bass
The bass will sound better outside the vehicle than in the front seats
I see this every day with crazy fiberglass builds and woofers pointed in all directions all for looks and no performance
Do mean to “DIS” I can see you have done a lot of work
Just giving you some input