The difference between 100 watts and 127 watts is 1dB. For what you're trying to accomplish, a bunch of coax speakers is the wrong approach. You should be looking at pro audio gear. I don't know if you can fit some small horns, but a redesign is in your best interest.No but I do...doing 80mph down the freeway, you won't hear a coax with only 100w.
I really think it's time for a DSP.