Back in the olden days 1991 I saw Rockford Fosgate's Demo Van, I believe it had ten 18" subs several Power 1000's, etc. Then shortly after I saw Mark Fukuda's Van
Mark Fukuda's Chevy Blazer - Show Cars - Car Audio and Electronics
Since I have seen many SPL vehicles and have even helped build a few. I saw a really loud SPL vehicle in Europe a few years back. It ran all Helix Audio. It was clean and loud. As of late, I came across an Ford Excursion running 16 10" T3's on Sundown amps.
There are people on this site with some very very loud set-ups.
I do not compete anymore and all of my cars are daily drivers. I do it for my love of audio. My current set-ups are (always changing):
-Suburban
H/U: Pioneer 7200BT
EQ: Rockford Fosgate EPX 2
Mids/Highs: 6.5" Memphis Audio x 4 / Memphis Audio Components x 4 / Memphis Audio 5x7" x 2
Subs: Six - 12 Memphis Mojos (Orange baskets..1000/2000...underated)
Amps (sub) Two - AudioQue 3500.1D / Amps (mids/highs): Two - Memphis 16-MCA5004
Electrical: Excessive Amperage 300 Amp Alt / 0/2 Custom Labeled Trystar x6 runs / Optima YT 34/78 front.... Stinger SPP2250 x 2 back
-Mitsubishi Pajero
H/U: JVC KW-AVX810
EQ: Rockford Fosgate PA2 and RF OEQ2
Mids/Highs: 6.5" MB Quart (old school) x 4
Subs: Two - 12" Rockford Fosgate HX2 (RFR-3112)
Amps: (Sub) Rockford Fosgate T20001BD (mids/highs): Rockford Fosgate T4004
Electrical: MechMan 200 Amp Alt / 0/1 Knu Kolossus x 4 runs / Optima YT 34/78 in front....Deka Intimidator x 2 back
-Odyssey
H/U: Alpine INA-W900 BT
EQ: Massive Audio EQ4P
Mids/Highs: Kenwood Excelon Components and 6.5" x 4
Subs: SA-12D4x 1
Amps: (Sub) Alpine MRX-M100 / (mids/highs): Kenwood KAC-8405
Electrical: Modified 140 amp Valeo Alt / 0/2 Custom Labeled Trystar x2 runs / Optima YT 34/78 front.... 31D Discovery Back x1
Project: 1976 VW Super Beatle - Old School Rockford Fosgate set-up Punch 150HD / Punch 45HD x2 / 12" Punch (inverted cone) / PA1 / etc still swapping out parts...will finish summer 2012