Battery help!

[jungstah]

Hey guys. So i don't have a voltmeter in my car...(noob move) and never knew whether my lights dimmed on bass hits because i have HID's and they don't dim. As i was playing my music earlier I opened the door and realized the interior lights all dimmed during bass. Therefore, I am planning to do big3 as well as put a beefier battery up front to replace my 4 year old interstate battery.

tl;dr

My questions:

What should I be looking for in a good battery UP FRONT? is it the AH rating and CCA rating? Should I strictly be looking at AGM batteries for any reason or is lead acid still ok? my system is in my sig, any suggestions for a good battery under or around $150?

[voltagexdt]

My humble opinion.. I run Optima.. I go for good reserve and good CCA