Upgrade time right around the corner! Advice needed!

[mylows10 5,000+ posts]

Well the Singer is 275 amp (310 Peak). I was going to run around 300 AH total (3 Batts) to begin with on 2500W on the SA's. Then strap the amp and get 2 more powerful subs adding another battery or 2 if needed. But, that is a ways off. The front stage takes precedence!

Should be fine

 

[trumpet 5,000+ posts]

Tundras can't take a CDT 6x9 without cutting the door panel. For now, you'll need to adapt for a round woofer.