As little a fan as I am of Audiobahn in general, the problem is more likely with the install (enclosure, wiring, charging system, cancellation issues or need for EQ, etc etc) than with the brand of speaker. I agree most Bahn stuff sounds bad (imo), but this doesn't sound like a SQ problem to me. Perhaps at high volume, the charging system's voltage drops too low to keep up with amplifier needs, for example.
But then again, it might just be the Audiobahn effect too. lol //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif