I hit 146.8db, street C legal on the TL at the Calgary 1x show a month ago in my 2001 z24 Cavalier.
Setup was a single DD 9515 off a strapped pair of AB 150.1s. 2.7cuft box tuned to 43Hz. G34 Crappy Tire batt up front, Odyssey 2150 in the back, 4 runs of 1/0 front to back, 2/0 to the amps.
That was with absolutely no testing, tuning, tweaking of any kind; I finished putting everything together 10 minutes before qualifying rounds started, and didn't even have time to properly set gains or see where I peaked before running. First pass was a 145.7 @ 45Hz, second pass of 46.8 was at 48Hz. Me thinks I have room to climb. I just need to quit taking vacations and stop being lazy lol!