I have 2 JBL GT5 12s in a t-line tuned at 30hz with 300rms going to it, and I had 2 5 1/4s and 2 6x9s running of the deck. I had to do away with the 5 1/4s and run the 6x9s off a second amp because the bass was drowning the mids and highs out, but the final set up I had, was 2 tweeters on my dash running off the front channel on my deck, 2 6x9s running 85rms a piece, and the 2 12s in the t-line on 300rms, that was a nice balance of bass and mid/highs. I could make almost anything sound good til some fuckers decided to steal my 6x9s now my stereo sounds like ass hope my rambling was helpful