4 12"s in a tahoe

try faceing the subs back, i also like a ported box made a huge difference in my car.i went from 2 12's sealed to 1 12 ported it hits alot hareder.

What id the total impediance the each amp is seeing? You say you have them wired correct but what is your definition of correct? if you have the amp seeing more than 4 ohms and the amp is bridged then you arent using the amp to its full potential. I have always hated the rockford bass knob that is included.. I ALLLWAYS leave that disconnected in every install I do for customers. Use the sub control on your deck(if its a good one) or your Equalizer(if you still run them old school things).
Lastly. How large is the box? separate chambers for each sub? If the subs share a chamber, make sure the subs sharing the chamber are wired to the same chanel of the amp. what are your low pass filters set for? if you are using the low pass on your deck or eq, then set the amplifier crossover to full. if your deck or eq has no crossover then use the filter in the amp.
Lastly, which punch amps are you using? you know there is a tiny gain adjustment besides the black knobs? I know alot of guys would think this is wreckless and dangerous, but I have had very favorable results by pushing these punch amps at less than 4 ohms...maybe if you got rid of the two amps and got one larger punch or power series amp you could make the subs beat a little harder... otherwise, a larger box, faced to the rear tailgate, or a correctly ported large box would make thing sound better. just trying to offer some possibilities.

i think the subs are 4 ohn i talked to a crutchfield guy and there a ton of help and walked me threw everything. ive been in the game for years but never wired up more then 2 subs. i know its ajust adding 2 more with another amp. the box is the right size built to the specs fosgate had with the subs and there is 4 chambers 1 for each sub. the amps i got are the old one withthe smooth metal face with the dull black inset in the ribs of the amp. when i flip the subs upside down do i have to make the box ported or is it the same as if the magnet where in the box?

ok there are a lot of factors that can cause what is going on. if you can email me and i can go over some things about your system. include model numbers and a scematic of your system. droopy101@hotmail.com

first off your using a 2 channel amp. it can only go down so far on the brigded load. you need a mono amp for each set, or one big one for all 4, I would use a JL 1000/1. What's your impedence load? 2 ohm,4 ohm, 8 0hm? sound's like they are at 8 ohm's or you got them wired out of phase? Also face them at the back hatch so they can load off of it.

i had 4 15s in my burban and it was not NEAR as loud as my 2 15s in my integra..its just cause its a bigger space man

the p3's are not that great to start off with

hell thats ur problem right there fukin p series in rockford.dude they r junk rockford is nuthin like they use to b the only thing rockford got thas worth a damn these days is the t series stuff.personally im a big fan of the re audio line i got 2 of there sx series 12s in my dodge 1500 just sittin in my back seat on a 2000 d class merlin us amp an my windshield flexs so personally id get rid of the punch an go with somethin better quality.

if i stood my box upright would it sound any louder? or if i cut my box in 2 and have 2 seperate boxes with 2 12's in each box an dmount themm differently what would work?

I would face them toward the rear of the truck.