Can anyone recommend a northern NJ car audio place that will competently install a phatbox (in my '02 M3 cab, HK) that I buy directly from phatnoise (I understand that there are no authorized dealers on the East Coast)?

Try http://www.phatnoise.com/forum/showthread.php?s=&threadid=798&perpage=15&pagenumber=2 for recommended installers